Crypto Functions
This module provides a set of cryptographic functions.
Note!
The actual supported algorithms and features depends on their availability in the actual libcrypto used. See the crypto (App) about dependencies.
Enabling FIPS mode will also disable algorithms and features.
The CRYPTO User's Guide has more information on FIPS, Engines and Algorithm Details like key lengths.
Types
cipher() = cipher_no_iv()  cipher_iv()  cipher_aead()
cipher_no_iv() =
aes_128_ecb  aes_192_ecb  aes_256_ecb  blowfish_ecb 
des_ecb  rc4
cipher_iv() =
aes_128_cbc  aes_192_cbc  aes_256_cbc  aes_128_cfb128 
aes_192_cfb128  aes_256_cfb128  aes_128_cfb8 
aes_192_cfb8  aes_256_cfb8  aes_128_ctr  aes_192_ctr 
aes_256_ctr  aes_ige256  blowfish_cbc  blowfish_cfb64 
blowfish_ofb64  chacha20  des_ede3_cbc  des_ede3_cfb 
des_cbc  des_cfb  rc2_cbc
cipher_aead() =
aes_128_ccm  aes_192_ccm  aes_256_ccm  aes_128_gcm 
aes_192_gcm  aes_256_gcm  chacha20_poly1305
Ciphers known by the CRYPTO application when using the new API.
Note that this list might be reduced if the underlying libcrypto does not support all of them.
block_cipher_with_iv() =
cbc_cipher()  cfb_cipher()  blowfish_ofb64  aes_ige256
block_cipher_without_iv() = ecb_cipher()
stream_cipher() = ctr_cipher()  chacha20  rc4
aead_cipher() = aes_gcm  aes_ccm  chacha20_poly1305
cbc_cipher() =
aes_128_cbc  aes_192_cbc  aes_256_cbc  blowfish_cbc 
des_cbc  des_ede3_cbc  rc2_cbc 
retired_cbc_cipher_aliases()
cfb_cipher() =
aes_128_cfb128  aes_192_cfb128  aes_256_cfb128 
aes_128_cfb8  aes_192_cfb8  aes_256_cfb8  blowfish_cfb64 
des_cfb  des_ede3_cfb 
retired_cfb_cipher_aliases()
ctr_cipher() =
aes_128_ctr  aes_192_ctr  aes_256_ctr 
retired_ctr_cipher_aliases()
ecb_cipher() =
aes_128_ecb  aes_192_ecb  aes_256_ecb  blowfish_ecb 
retired_ecb_cipher_aliases()
Ciphers known by the CRYPTO application when using the old API.
Note that this list might be reduced if the underlying libcrypto does not support all of them.
retired_cbc_cipher_aliases() =
aes_cbc  aes_cbc128  aes_cbc256  des3_cbc  des_ede3
retired_cfb_cipher_aliases() =
aes_cfb8  aes_cfb128  des3_cbf  des3_cfb  des_ede3_cbf
retired_ctr_cipher_aliases() = aes_ctr
retired_ecb_cipher_aliases() = aes_ecb
Alternative, old names of ciphers known by the CRYPTO application when using the old API. See Retired cipher names for names to use instead to be prepared for an easy convertion to the new API.
Note that this list might be reduced if the underlying libcrypto does not support all of them.
hash_algorithm() =
sha1() 
sha2() 
sha3() 
blake2() 
ripemd160 
compatibility_only_hash()
hmac_hash_algorithm() =
sha1()  sha2()  sha3()  compatibility_only_hash()
sha1() = sha
sha2() = sha224  sha256  sha384  sha512
sha3() = sha3_224  sha3_256  sha3_384  sha3_512
blake2() = blake2b  blake2s
compatibility_only_hash() = md5  md4
The compatibility_only_hash()
algorithms are recommended only for compatibility with existing applications.
ec_named_curve() =
brainpoolP160r1  brainpoolP160t1  brainpoolP192r1 
brainpoolP192t1  brainpoolP224r1  brainpoolP224t1 
brainpoolP256r1  brainpoolP256t1  brainpoolP320r1 
brainpoolP320t1  brainpoolP384r1  brainpoolP384t1 
brainpoolP512r1  brainpoolP512t1  c2pnb163v1  c2pnb163v2 
c2pnb163v3  c2pnb176v1  c2pnb208w1  c2pnb272w1 
c2pnb304w1  c2pnb368w1  c2tnb191v1  c2tnb191v2 
c2tnb191v3  c2tnb239v1  c2tnb239v2  c2tnb239v3 
c2tnb359v1  c2tnb431r1  ipsec3  ipsec4  prime192v1 
prime192v2  prime192v3  prime239v1  prime239v2 
prime239v3  prime256v1  secp112r1  secp112r2  secp128r1 
secp128r2  secp160k1  secp160r1  secp160r2  secp192k1 
secp192r1  secp224k1  secp224r1  secp256k1  secp256r1 
secp384r1  secp521r1  sect113r1  sect113r2  sect131r1 
sect131r2  sect163k1  sect163r1  sect163r2  sect193r1 
sect193r2  sect233k1  sect233r1  sect239k1  sect283k1 
sect283r1  sect409k1  sect409r1  sect571k1  sect571r1 
wtls1  wtls10  wtls11  wtls12  wtls3  wtls4  wtls5 
wtls6  wtls7  wtls8  wtls9
edwards_curve_dh() = x25519  x448
edwards_curve_ed() = ed25519  ed448
Note that some curves are disabled if FIPS is enabled.
ec_explicit_curve() =
{Field :: ec_field(),
Curve :: ec_curve(),
BasePoint :: binary(),
Order :: binary(),
CoFactor :: none  binary()}
ec_field() = ec_prime_field()  ec_characteristic_two_field()
ec_curve() =
{A :: binary(), B :: binary(), Seed :: none  binary()}
Parametric curve definition.
ec_prime_field() = {prime_field, Prime :: integer()}
ec_characteristic_two_field() =
{characteristic_two_field,
M :: integer(),
Basis :: ec_basis()}
ec_basis() =
{tpbasis, K :: integer() >= 0} 
{ppbasis,
K1 :: integer() >= 0,
K2 :: integer() >= 0,
K3 :: integer() >= 0} 
onbasis
Curve definition details.
key() = iodata()
des3_key() = [key()]
For keylengths, ivsizes and blocksizes see the User's Guide.
A key for des3 is a list of three iolists
key_integer() = integer()  binary()
Always binary()
when used as return value
rsa_public() = [key_integer()]
rsa_private() = [key_integer()]
rsa_params() =
{ModulusSizeInBits :: integer(),
PublicExponent :: key_integer()}
rsa_public() = [E, N]
rsa_private() = [E, N, D]  [E, N, D, P1, P2, E1, E2, C]
Where E is the public exponent, N is public modulus and D is
the private exponent. The longer key format contains redundant
information that will make the calculation faster. P1,P2 are first
and second prime factors. E1,E2 are first and second exponents. C
is the CRT coefficient. Terminology is taken from
dss_public() = [key_integer()]
dss_private() = [key_integer()]
dss_public() = [P, Q, G, Y]
Where P, Q and G are the dss parameters and Y is the public key.
dss_private() = [P, Q, G, X]
Where P, Q and G are the dss parameters and X is the private key.
ecdsa_public() = key_integer()
ecdsa_private() = key_integer()
ecdsa_params() = ec_named_curve()  ec_explicit_curve()
srp_public() = key_integer()
srp_private() = key_integer()
srp_public() = key_integer()
Where is A
or B
from
srp_private() = key_integer()
Where is a
or b
from
srp_gen_params() =
{user, srp_user_gen_params()}  {host, srp_host_gen_params()}
srp_comp_params() =
{user, srp_user_comp_params()} 
{host, srp_host_comp_params()}
srp_user_gen_params() = [DerivedKey::binary(), Prime::binary(), Generator::binary(), Version::atom()]
srp_host_gen_params() = [Verifier::binary(), Prime::binary(), Version::atom() ]
srp_user_comp_params() = [DerivedKey::binary(), Prime::binary(), Generator::binary(), Version::atom()  ScramblerArg::list()]
srp_host_comp_params() = [Verifier::binary(), Prime::binary(), Version::atom()  ScramblerArg::list()]
Where Verifier is v
, Generator is g
and Prime is N
, DerivedKey is X
, and Scrambler is
u
(optional will be generated if not provided) from
pk_encrypt_decrypt_algs() = rsa
Algorithms for public key encrypt/decrypt. Only RSA is supported.
pk_encrypt_decrypt_opts() = [rsa_opt()]  rsa_compat_opts()
rsa_opt() =
{rsa_padding, rsa_padding()} 
{signature_md, atom()} 
{rsa_mgf1_md, sha} 
{rsa_oaep_label, binary()} 
{rsa_oaep_md, sha}
rsa_padding() =
rsa_pkcs1_padding  rsa_pkcs1_oaep_padding 
rsa_sslv23_padding  rsa_x931_padding  rsa_no_padding
Options for public key encrypt/decrypt. Only RSA is supported.
Warning!
The RSA options are experimental.
The exact set of options and there syntax may be changed without prior notice.
rsa_compat_opts() = [{rsa_pad, rsa_padding()}]  rsa_padding()
Those option forms are kept only for compatibility and should not be used in new code.
pk_sign_verify_algs() = rsa  dss  ecdsa  eddsa
Algorithms for sign and verify.
pk_sign_verify_opts() = [rsa_sign_verify_opt()]
rsa_sign_verify_opt() =
{rsa_padding, rsa_sign_verify_padding()} 
{rsa_pss_saltlen, integer()} 
{rsa_mgf1_md, sha2()}
rsa_sign_verify_padding() =
rsa_pkcs1_padding  rsa_pkcs1_pss_padding  rsa_x931_padding 
rsa_no_padding
Options for sign and verify.
Warning!
The RSA options are experimental.
The exact set of options and there syntax may be changed without prior notice.
dh_params() = [key_integer()]
dh_params() = [P, G]  [P, G, PrivateKeyBitLength]
ecdh_public() = key_integer()
ecdh_private() = key_integer()
ecdh_params() =
ec_named_curve()  edwards_curve_dh()  ec_explicit_curve()
engine_key_ref() =
#{engine := engine_ref(),
key_id := key_id(),
password => password(),
term() => term()}
engine_ref() = term()
The result of a call to engine_load/3.
key_id() = string()  binary()
Identifies the key to be used. The format depends on the loaded engine. It is passed to
the ENGINE_load_(privatepublic)_key
functions in libcrypto.
password() = string()  binary()
The password of the key stored in an engine.
engine_method_type() =
engine_method_rsa  engine_method_dsa  engine_method_dh 
engine_method_rand  engine_method_ecdh 
engine_method_ecdsa  engine_method_ciphers 
engine_method_digests  engine_method_store 
engine_method_pkey_meths  engine_method_pkey_asn1_meths 
engine_method_ec
engine_cmnd() = {unicode:chardata(), unicode:chardata()}
Pre and Post commands for engine_load/3 and /4.
stream_state()
hmac_state()
hash_state()
crypto_state()
Contexts with an internal state that should not be manipulated but passed between function calls.
run_time_error() = no_return()
The exception error:badarg
signifies that one or more arguments are of wrong data type,
or are otherwise badly formed.
The exception error:notsup
signifies that the algorithm is known but is not supported
by current underlying libcrypto or explicitly disabled when building that.
For a list of supported algorithms, see supports/0.
descriptive_error() = no_return()
This is a more developed variant of the older run_time_error().
The exception is:
{Tag, {C_FileName,LineNumber}, Description} Tag = badarg  notsup  error C_FileName = string() LineNumber = integer() Description = string()
It is like the older type an exception of the error
class. In addition they contain
a descriptive text in English. That text is targeted to a developer. Examples are "Bad key size"
or "Cipher id is not an atom".
The exception tags are:
badarg
Signifies that one or more arguments are of wrong data type or are otherwise badly formed.
notsup
Signifies that the algorithm is known but is not supported by current underlying libcrypto or explicitly disabled when building that one.
error
An error condition that should not occur, for example a memory allocation failed or the underlying cryptolib returned an error code, for example "Can't initialize context, step 1". Thoose text usually needs searching the Ccode to be understood.
To catch the exception, use for example:
try crypto:crypto_init(Ciph, Key, IV, true)
catch
error:{Tag, {C_FileName,LineNumber}, Description} >
do_something(......)
.....
end
New API
Functions
crypto_init(Cipher, Key, EncryptFlag) >
State  descriptive_error()
Cipher = cipher_no_iv()
Key = iodata()
EncryptFlag = boolean()
State = crypto_state()
As crypto_init/4 but for ciphers without IVs.
crypto_init(Cipher, Key, IV, EncryptFlag) >
State  descriptive_error()
Cipher = cipher_iv()
Key = IV = iodata()
EncryptFlag = boolean()
State = crypto_state()
Part of the new API. Initializes a series of encryptions or decryptions and creates an internal state with a reference that is returned. The actual encryption or decryption is done by crypto_update/2.
For encryption, set the EncryptFlag
to true
. For decryption, set it to false
.
crypto_update(State, Data) > Result  descriptive_error()
State = crypto_state()
Data = iodata()
Result = binary()
Part of the new API.
It does an actual crypto operation on a part of the full text. If the part is less
than a number of full blocks, only the full blocks (possibly none) are encrypted
or decrypted and the remaining bytes are saved to the next crypto_update
operation.
The State
should be created with
crypto_init/3
or
crypto_init/4.
crypto_dyn_iv_init(Cipher, Key, EncryptFlag) >
State  descriptive_error()
Cipher = cipher_iv()
Key = iodata()
EncryptFlag = boolean()
State = crypto_state()
Part of the new API. Initializes a series of encryptions or decryptions where the IV is provided later. The actual encryption or decryption is done by crypto_dyn_iv_update/3.
For encryption, set the EncryptFlag
to true
. For decryption, set it to false
.
crypto_dyn_iv_update(State, Data, IV) >
Result  descriptive_error()
State = crypto_state()
Data = IV = iodata()
Result = binary()
Part of the new API.
Do an actual crypto operation on a part of the full text and the IV is supplied for each part.
The State
should be created with
crypto_dyn_iv_init/3.
crypto_one_time(Cipher, Key, Data, EncryptFlag) >
Result  descriptive_error()
Cipher = cipher_no_iv()
Key = Data = iodata()
EncryptFlag = boolean()
Result = binary()
As crypto_one_time/5 but for ciphers without IVs.
crypto_one_time(Cipher, Key, IV, Data, EncryptFlag) >
Result  descriptive_error()
Cipher = cipher_iv()
Key = IV = Data = iodata()
EncryptFlag = boolean()
Result = binary()
Part of the new API.
Do a complete encrypt or decrypt of the full text in the argument Data
.
For encryption, set the EncryptFlag
to true
. For decryption, set it to false
.
crypto_one_time_aead(Cipher, Key, IV, InText, AAD,
EncFlag :: true) >
Result  descriptive_error()
Cipher = cipher_aead()
Key = IV = InText = AAD = iodata()
Result = EncryptResult
EncryptResult = {OutCryptoText, OutTag}
OutCryptoText = OutTag = binary()
crypto_one_time_aead(Cipher, Key, IV, InText, AAD, TagOrTagLength,
EncFlag) >
Result  descriptive_error()
Cipher = cipher_aead()
Key = IV = InText = AAD = iodata()
TagOrTagLength = EncryptTagLength  DecryptTag
EncryptTagLength = integer() >= 0
DecryptTag = iodata()
EncFlag = boolean()
Result = EncryptResult  DecryptResult
EncryptResult = {OutCryptoText, OutTag}
DecryptResult = OutPlainText  error
OutCryptoText = OutTag = OutPlainText = binary()
Part of the new API. Do a complete encrypt or decrypt with an AEAD cipher of the full text.
For encryption, set the EncryptFlag
to true
and set the TagOrTagLength
to the wanted size of the tag, that is, the tag length. If the default length is wanted, the
crypto_aead/6
form may be used.
For decryption, set the EncryptFlag
to false
and put the tag to be checked
in the argument TagOrTagLength
.
supports(Type) > Support
Type = hashs  ciphers  public_keys  macs  curves  rsa_opts
Support = Hashs  Ciphers  PKs  Macs  Curves  RSAopts
Hashs =
[sha1() 
sha2() 
sha3() 
blake2() 
ripemd160 
compatibility_only_hash()]Ciphers = [cipher()]
PKs = [rsa  dss  ecdsa  dh  ecdh  ec_gf2m]
Macs = [hmac  cmac  poly1305]
Curves =
[ec_named_curve()  edwards_curve_dh()  edwards_curve_ed()]RSAopts = [rsa_sign_verify_opt()  rsa_opt()]
Can be used to determine which crypto algorithms that are supported by the underlying libcrypto library
See hash_info/1 and cipher_info/1 for information about the hash and cipher algorithms.
API kept from previous versions
Functions
bytes_to_integer(Bin :: binary()) > integer()
Convert binary representation, of an integer, to an Erlang integer.
compute_key(Type, OthersPublicKey, MyPrivateKey, Params) >
SharedSecret
Type = dh  ecdh  srp
SharedSecret = binary()
OthersPublicKey = dh_public()  ecdh_public()  srp_public()
MyPrivateKey =
dh_private()  ecdh_private()  {srp_public(), srp_private()}Params = dh_params()  ecdh_params()  srp_comp_params()
Computes the shared secret from the private key and the other party's public key. See also public_key:compute_key/2
exor(Bin1 :: iodata(), Bin2 :: iodata()) > binary()
Performs bitwise XOR (exclusive or) on the data supplied.
generate_key(Type, Params) > {PublicKey, PrivKeyOut}
Type = dh  ecdh  rsa  srp
PublicKey =
dh_public()  ecdh_public()  rsa_public()  srp_public()PrivKeyOut =
dh_private() 
ecdh_private() 
rsa_private() 
{srp_public(), srp_private()}Params =
dh_params()  ecdh_params()  rsa_params()  srp_gen_params()
generate_key(Type, Params, PrivKeyIn) > {PublicKey, PrivKeyOut}
Type = dh  ecdh  rsa  srp
PublicKey =
dh_public()  ecdh_public()  rsa_public()  srp_public()PrivKeyIn =
undefined 
dh_private() 
ecdh_private() 
rsa_private() 
{srp_public(), srp_private()}PrivKeyOut =
dh_private() 
ecdh_private() 
rsa_private() 
{srp_public(), srp_private()}Params =
dh_params()  ecdh_params()  rsa_params()  srp_comp_params()
Generates a public key of type Type
.
See also public_key:generate_key/1.
May raise exception:
error:badarg
: an argument is of wrong type or has an illegal value,error:low_entropy
: the random generator failed due to lack of secure "randomness",error:computation_failed
: the computation fails of another reason thanlow_entropy
.
Note!
RSA key generation is only available if the runtime was
built with dirty scheduler support. Otherwise, attempting to
generate an RSA key will raise exception error:notsup
.
hash(Type, Data) > Digest
Type = hash_algorithm()
Data = iodata()
Digest = binary()
Computes a message digest of type Type
from Data
.
May raise exception error:notsup
in case the chosen Type
is not supported by the underlying libcrypto implementation.
hash_init(Type) > State
Type = hash_algorithm()
State = hash_state()
Initializes the context for streaming hash operations. Type
determines
which digest to use. The returned context should be used as argument
to hash_update.
May raise exception error:notsup
in case the chosen Type
is not supported by the underlying libcrypto implementation.
hash_update(State, Data) > NewState
State = NewState = hash_state()
Data = iodata()
Updates the digest represented by Context
using the given Data
. Context
must have been generated using hash_init
or a previous call to this function. Data
can be any length. NewContext
must be passed into the next call to hash_update
or hash_final.
hash_final(State) > Digest
State = hash_state()
Digest = binary()
Finalizes the hash operation referenced by Context
returned
from a previous call to hash_update.
The size of Digest
is determined by the type of hash
function used to generate it.
hmac(Type, Key, Data) > Mac
Type = hmac_hash_algorithm()
Key = Data = iodata()
Mac = binary()
hmac(Type, Key, Data, MacLength) > Mac
Type = hmac_hash_algorithm()
Key = Data = iodata()
MacLength = integer()
Mac = binary()
Computes a HMAC of type Type
from Data
using
Key
as the authentication key.
MacLength
will limit the size of the resultant Mac
.
hmac_init(Type, Key) > State
Type = hmac_hash_algorithm()
Key = iodata()
State = hmac_state()
Initializes the context for streaming HMAC operations. Type
determines
which hash function to use in the HMAC operation. Key
is the authentication
key. The key can be any length.
hmac_update(State, Data) > NewState
Data = iodata()
State = NewState = hmac_state()
Updates the HMAC represented by Context
using the given Data
. Context
must have been generated using an HMAC init function (such as
hmac_init). Data
can be any length. NewContext
must be passed into the next call to hmac_update
or to one of the functions hmac_final and
hmac_final_n
Warning!
Do not use a Context
as argument in more than one
call to hmac_update or hmac_final. The semantics of reusing old contexts
in any way is undefined and could even crash the VM in earlier releases.
The reason for this limitation is a lack of support in the underlying
libcrypto API.
hmac_final(State) > Mac
State = hmac_state()
Mac = binary()
Finalizes the HMAC operation referenced by Context
. The size of the resultant MAC is
determined by the type of hash function used to generate it.
hmac_final_n(State, HashLen) > Mac
State = hmac_state()
HashLen = integer()
Mac = binary()
Finalizes the HMAC operation referenced by Context
. HashLen
must be greater than
zero. Mac
will be a binary with at most HashLen
bytes. Note that if HashLen is greater than the actual number of bytes returned from the underlying hash, the returned hash will have fewer than HashLen
bytes.
cmac(Type, Key, Data) > Mac
Type =
cbc_cipher() 
cfb_cipher() 
blowfish_cbc  des_ede3  rc2_cbcKey = Data = iodata()
Mac = binary()
cmac(Type, Key, Data, MacLength) > Mac
Type =
cbc_cipher() 
cfb_cipher() 
blowfish_cbc  des_ede3  rc2_cbcKey = Data = iodata()
MacLength = integer()
Mac = binary()
Computes a CMAC of type Type
from Data
using
Key
as the authentication key.
MacLength
will limit the size of the resultant Mac
.
info_fips() > not_supported  not_enabled  enabled
Provides information about the FIPS operating status of
crypto and the underlying libcrypto library. If crypto was built
with FIPS support this can be either enabled
(when
running in FIPS mode) or not_enabled
. For other builds
this value is always not_supported
.
See enable_fips_mode/1 about how to enable FIPS mode.
Warning!
In FIPS mode all nonFIPS compliant algorithms are
disabled and raise exception error:notsup
. Check
supports that in
FIPS mode returns the restricted list of available
algorithms.
enable_fips_mode(Enable) > Result
Enable = Result = boolean()
Enables (Enable = true
) or disables (Enable = false
) FIPS mode. Returns true
if
the operation was successful or false
otherwise.
Note that to enable FIPS mode succesfully, OTP must be built with the configure option enablefips
,
and the underlying libcrypto must also support FIPS.
See also info_fips/0.
info_lib() > [{Name, VerNum, VerStr}]
Name = binary()
VerNum = integer()
VerStr = binary()
Provides the name and version of the libraries used by crypto.
Name
is the name of the library. VerNum
is
the numeric version according to the library's own versioning
scheme. VerStr
contains a text variant of the version.
> info_lib().
[{<<"OpenSSL">>,269484095,<<"OpenSSL 1.1.0c 10 Nov 2016"">>}]
Note!
From OTP R16 the numeric version represents the version of the OpenSSL
header files (openssl/opensslv.h
) used when crypto was compiled.
The text variant represents the libcrypto library used at runtime.
In earlier OTP versions both numeric and text was taken from the library.
hash_info(Type) > Result  run_time_error()
Type = hash_algorithm()
Result =
#{size := integer(),
block_size := integer(),
type := integer()}
Provides a map with information about block_size, size and possibly other properties of the hash algorithm in question.
For a list of supported hash algorithms, see supports/0.
cipher_info(Type) > Result  run_time_error()
Type = cipher()
Result =
#{key_length := integer(),
iv_length := integer(),
block_size := integer(),
mode := CipherModes,
type := undefined  integer()}CipherModes =
undefined  cbc_mode  ccm_mode  cfb_mode  ctr_mode 
ecb_mode  gcm_mode  ige_mode  ocb_mode  ofb_mode 
wrap_mode  xts_mode
Provides a map with information about block_size, key_length, iv_length and possibly other properties of the cipher algorithm in question.
Note!
The ciphers aes_cbc
, aes_cfb8
, aes_cfb128
, aes_ctr
,
aes_ecb
, aes_gcm
and aes_ccm
has no keylength in the Type
as opposed to for example aes_128_ctr
. They adapt to the length of
the key provided in the encrypt and decrypt function. Therefor it is impossible to return a valid keylength
in the map.
Always use a Type
with an explicit key length,
For a list of supported cipher algorithms, see supports/0.
mod_pow(N, P, M) > Result
N = P = M = binary()  integer()
Result = binary()  error
Computes the function N^P mod M
.
next_iv(Type :: cbc_cipher(), Data) > NextIVec
Data = iodata()
NextIVec = binary()
next_iv(Type :: des_cfb, Data, IVec) > NextIVec
Data = iodata()
IVec = NextIVec = binary()
Returns the initialization vector to be used in the next
iteration of encrypt/decrypt of type Type
. Data
is the
encrypted data from the previous iteration step. The IVec
argument is only needed for des_cfb
as the vector used
in the previous iteration step.
poly1305(Key :: iodata(), Data :: iodata()) > Mac
Mac = binary()
Computes a POLY1305 message authentication code (Mac
) from Data
using
Key
as the authentication key.
private_decrypt(Algorithm, CipherText, PrivateKey, Options) >
PlainText
Algorithm = pk_encrypt_decrypt_algs()
CipherText = binary()
PrivateKey = rsa_private()  engine_key_ref()
Options = pk_encrypt_decrypt_opts()
PlainText = binary()
Decrypts the CipherText
, encrypted with
public_encrypt/4 (or equivalent function)
using the PrivateKey
, and returns the
plaintext (message digest). This is a low level signature verification operation
used for instance by older versions of the SSL protocol.
See also public_key:decrypt_private/[2,3]
private_encrypt(Algorithm, PlainText, PrivateKey, Options) >
CipherText
Algorithm = pk_encrypt_decrypt_algs()
PlainText = binary()
PrivateKey = rsa_private()  engine_key_ref()
Options = pk_encrypt_decrypt_opts()
CipherText = binary()
Encrypts the PlainText
using the PrivateKey
and returns the ciphertext. This is a low level signature operation
used for instance by older versions of the SSL protocol. See
also public_key:encrypt_private/[2,3]
public_decrypt(Algorithm, CipherText, PublicKey, Options) >
PlainText
Algorithm = pk_encrypt_decrypt_algs()
CipherText = binary()
PublicKey = rsa_public()  engine_key_ref()
Options = pk_encrypt_decrypt_opts()
PlainText = binary()
Decrypts the CipherText
, encrypted with
private_encrypt/4(or equivalent function)
using the PrivateKey
, and returns the
plaintext (message digest). This is a low level signature verification operation
used for instance by older versions of the SSL protocol.
See also public_key:decrypt_public/[2,3]
public_encrypt(Algorithm, PlainText, PublicKey, Options) >
CipherText
Algorithm = pk_encrypt_decrypt_algs()
PlainText = binary()
PublicKey = rsa_public()  engine_key_ref()
Options = pk_encrypt_decrypt_opts()
CipherText = binary()
Encrypts the PlainText
(message digest) using the PublicKey
and returns the CipherText
. This is a low level signature operation
used for instance by older versions of the SSL protocol. See also public_key:encrypt_public/[2,3]
rand_seed(Seed :: binary()) > ok
Set the seed for PRNG to the given binary. This calls the
RAND_seed function from openssl. Only use this if the system
you are running on does not have enough "randomness" built in.
Normally this is when
strong_rand_bytes/1
raises error:low_entropy
Lo, Hi, N = integer()
Generate a random number N, Lo =< N < Hi.
Uses the
crypto
library pseudorandom number generator.
Hi
must be larger than Lo
.
start() > ok  {error, Reason :: term()}
Equivalent to application:start(crypto).
stop() > ok  {error, Reason :: term()}
Equivalent to application:stop(crypto).
strong_rand_bytes(N :: integer() >= 0) > binary()
Generates N bytes randomly uniform 0..255, and returns the
result in a binary. Uses a cryptographically secure prng seeded and
periodically mixed with operating system provided entropy. By default
this is the RAND_bytes
method from OpenSSL.
May raise exception error:low_entropy
in case the random generator
failed due to lack of secure "randomness".
rand_seed() > rand:state()
Creates state object for
random number generation,
in order to generate cryptographically strong random numbers
(based on OpenSSL's BN_rand_range
),
and saves it in the process dictionary before returning it as well.
See also
rand:seed/1 and
rand_seed_s/0.
When using the state object from this function the
rand functions using it
may raise exception error:low_entropy
in case the random generator
failed due to lack of secure "randomness".
Example
_ = crypto:rand_seed(), _IntegerValue = rand:uniform(42), % [1; 42] _FloatValue = rand:uniform(). % [0.0; 1.0[
rand_seed_s() > rand:state()
Creates state object for
random number generation,
in order to generate cryptographically strongly random numbers
(based on OpenSSL's BN_rand_range
).
See also
rand:seed_s/1.
When using the state object from this function the
rand functions using it
may raise exception error:low_entropy
in case the random generator
failed due to lack of secure "randomness".
Note!
The state returned from this function cannot be used to get a reproducable random sequence as from the other rand functions, since reproducability does not match cryptographically safe.
The only supported usage is to generate one distinct random sequence from this start state.
Alg = crypto  crypto_cache
Creates state object for random number generation, in order to generate cryptographically strong random numbers, and saves it in the process dictionary before returning it as well. See also rand:seed/1 and rand_seed_alg_s/1.
When using the state object from this function the
rand functions using it
may raise exception error:low_entropy
in case the random generator
failed due to lack of secure "randomness".
Example
_ = crypto:rand_seed_alg(crypto_cache), _IntegerValue = rand:uniform(42), % [1; 42] _FloatValue = rand:uniform(). % [0.0; 1.0[
Alg = crypto_aes
Creates a state object for random number generation, in order to generate cryptographically unpredictable random numbers, and saves it in the process dictionary before returning it as well. See also rand_seed_alg_s/2.
Example
_ = crypto:rand_seed_alg(crypto_aes, "my seed"), IntegerValue = rand:uniform(42), % [1; 42] FloatValue = rand:uniform(), % [0.0; 1.0[ _ = crypto:rand_seed_alg(crypto_aes, "my seed"), IntegerValue = rand:uniform(42), % Same values FloatValue = rand:uniform(). % again
Alg = crypto  crypto_cache
Creates state object for random number generation, in order to generate cryptographically strongly random numbers. See also rand:seed_s/1.
If Alg
is crypto
this function behaves exactly like
rand_seed_s/0.
If Alg
is crypto_cache
this function
fetches random data with OpenSSL's RAND_bytes
and caches it for speed using an internal word size
of 56 bits that makes calculations fast on 64 bit machines.
When using the state object from this function the
rand functions using it
may raise exception error:low_entropy
in case the random generator
failed due to lack of secure "randomness".
The cache size can be changed from its default value using the
crypto app's
configuration parameter rand_cache_size
.
When using the state object from this function the
rand functions using it
may throw exception low_entropy
in case the random generator
failed due to lack of secure "randomness".
Note!
The state returned from this function cannot be used to get a reproducable random sequence as from the other rand functions, since reproducability does not match cryptographically safe.
In fact since random data is cached some numbers may get reproduced if you try, but this is unpredictable.
The only supported usage is to generate one distinct random sequence from this start state.
Alg = crypto_aes
Creates a state object for random number generation, in order to generate cryptographically unpredictable random numbers. See also rand_seed_alg/1.
To get a long period the Xoroshiro928 generator from the rand module is used as a counter (with period 2^928  1) and the generator states are scrambled through AES to create 58bit pseudo random values.
The result should be statistically completely unpredictable random values, since the scrambling is cryptographically strong and the period is ridiculously long. But the generated numbers are not to be regarded as cryptographically strong since there is no rekeying schedule.

If you need cryptographically strong random numbers use rand_seed_alg_s/1 with
Alg =:= crypto
orAlg =:= crypto_cache
. 
If you need to be able to repeat the sequence use this function.

If you do not need the statistical quality of this function, there are faster algorithms in the rand module.
Thanks to the used generator the state object supports the
rand:jump/0,1
function with distance 2^512.
Numbers are generated in batches and cached for speed reasons.
The cache size can be changed from its default value using the
crypto app's
configuration parameter rand_cache_size
.
ec_curves() > [EllipticCurve]
EllipticCurve =
ec_named_curve()  edwards_curve_dh()  edwards_curve_ed()
Can be used to determine which named elliptic curves are supported.
ec_curve(CurveName) > ExplicitCurve
CurveName = ec_named_curve()
ExplicitCurve = ec_explicit_curve()
Return the defining parameters of a elliptic curve.
sign(Algorithm, DigestType, Msg, Key) > Signature
Algorithm = pk_sign_verify_algs()
DigestType =
rsa_digest_type()  dss_digest_type()  ecdsa_digest_type()Msg = iodata()  {digest, iodata()}
Key =
rsa_private() 
dss_private() 
[ecdsa_private()  ecdsa_params()] 
[eddsa_private()  eddsa_params()] 
engine_key_ref()Signature = binary()
sign(Algorithm, DigestType, Msg, Key, Options) > Signature
Algorithm = pk_sign_verify_algs()
DigestType =
rsa_digest_type() 
dss_digest_type() 
ecdsa_digest_type() 
noneMsg = iodata()  {digest, iodata()}
Key =
rsa_private() 
dss_private() 
[ecdsa_private()  ecdsa_params()] 
[eddsa_private()  eddsa_params()] 
engine_key_ref()Options = pk_sign_verify_opts()
Signature = binary()
Creates a digital signature.
The msg is either the binary "cleartext" data to be signed or it is the hashed value of "cleartext" i.e. the digest (plaintext).
Algorithm dss
can only be used together with digest type
sha
.
See also public_key:sign/3.
verify(Algorithm, DigestType, Msg, Signature, Key) > Result
Algorithm = pk_sign_verify_algs()
DigestType =
rsa_digest_type() 
dss_digest_type() 
ecdsa_digest_type() 
noneMsg = iodata()  {digest, iodata()}
Signature = binary()
Key =
rsa_public() 
dss_public() 
[ecdsa_public()  ecdsa_params()] 
[eddsa_public()  eddsa_params()] 
engine_key_ref()Result = boolean()
verify(Algorithm, DigestType, Msg, Signature, Key, Options) >
Result
Algorithm = pk_sign_verify_algs()
DigestType =
rsa_digest_type()  dss_digest_type()  ecdsa_digest_type()Msg = iodata()  {digest, iodata()}
Signature = binary()
Key =
rsa_public() 
dss_public() 
[ecdsa_public()  ecdsa_params()] 
[eddsa_public()  eddsa_params()] 
engine_key_ref()Options = pk_sign_verify_opts()
Result = boolean()
Verifies a digital signature
The msg is either the binary "cleartext" data to be signed or it is the hashed value of "cleartext" i.e. the digest (plaintext).
Algorithm dss
can only be used together with digest type
sha
.
See also public_key:verify/4.
Engine API
Functions
privkey_to_pubkey(Type, EnginePrivateKeyRef) > PublicKey
Type = rsa  dss
EnginePrivateKeyRef = engine_key_ref()
PublicKey = rsa_public()  dss_public()
Fetches the corresponding public key from a private key stored in an Engine. The key must be of the type indicated by the Type parameter.
engine_get_all_methods() > Result
Result = [engine_method_type()]
Returns a list of all possible engine methods.
May raise exception error:notsup
in case there is
no engine support in the underlying OpenSSL implementation.
See also the chapter Engine Load in the User's Guide.
engine_load(EngineId, PreCmds, PostCmds) > Result
EngineId = unicode:chardata()
PreCmds = PostCmds = [engine_cmnd()]
Result =
{ok, Engine :: engine_ref()}  {error, Reason :: term()}
Loads the OpenSSL engine given by EngineId
if it is available and then returns ok and
an engine handle. This function is the same as calling engine_load/4
with
EngineMethods
set to a list of all the possible methods. An error tuple is
returned if the engine can't be loaded.
The function raises a error:badarg
if the parameters are in wrong format.
It may also raise the exception error:notsup
in case there is
no engine support in the underlying OpenSSL implementation.
See also the chapter Engine Load in the User's Guide.
engine_load(EngineId, PreCmds, PostCmds, EngineMethods) > Result
EngineId = unicode:chardata()
PreCmds = PostCmds = [engine_cmnd()]
EngineMethods = [engine_method_type()]
Result =
{ok, Engine :: engine_ref()}  {error, Reason :: term()}
Loads the OpenSSL engine given by EngineId
if it is available and then returns ok and
an engine handle. An error tuple is returned if the engine can't be loaded.
The function raises a error:badarg
if the parameters are in wrong format.
It may also raise the exception error:notsup
in case there is
no engine support in the underlying OpenSSL implementation.
See also the chapter Engine Load in the User's Guide.
engine_unload(Engine) > Result
Engine = engine_ref()
Result = ok  {error, Reason :: term()}
Unloads the OpenSSL engine given by Engine
.
An error tuple is returned if the engine can't be unloaded.
The function raises a error:badarg
if the parameter is in wrong format.
It may also raise the exception error:notsup
in case there is
no engine support in the underlying OpenSSL implementation.
See also the chapter Engine Load in the User's Guide.
engine_by_id(EngineId) > Result
EngineId = unicode:chardata()
Result =
{ok, Engine :: engine_ref()}  {error, Reason :: term()}
Get a reference to an already loaded engine with EngineId
.
An error tuple is returned if the engine can't be unloaded.
The function raises a error:badarg
if the parameter is in wrong format.
It may also raise the exception error:notsup
in case there is
no engine support in the underlying OpenSSL implementation.
See also the chapter Engine Load in the User's Guide.
engine_ctrl_cmd_string(Engine, CmdName, CmdArg) > Result
Engine = term()
CmdName = CmdArg = unicode:chardata()
Result = ok  {error, Reason :: term()}
Sends ctrl commands to the OpenSSL engine given by Engine
.
This function is the same as calling engine_ctrl_cmd_string/4
with
Optional
set to false
.
The function raises a error:badarg
if the parameters are in wrong format.
It may also raise the exception error:notsup
in case there is
no engine support in the underlying OpenSSL implementation.
engine_ctrl_cmd_string(Engine, CmdName, CmdArg, Optional) >
Result
Engine = term()
CmdName = CmdArg = unicode:chardata()
Optional = boolean()
Result = ok  {error, Reason :: term()}
Sends ctrl commands to the OpenSSL engine given by Engine
.
Optional
is a boolean argument that can relax the semantics of the function.
If set to true
it will only return failure if the ENGINE supported the given
command name but failed while executing it, if the ENGINE doesn't support the command
name it will simply return success without doing anything. In this case we assume
the user is only supplying commands specific to the given ENGINE so we set this to
false
.
The function raises a error:badarg
if the parameters are in wrong format.
It may also raise the exception error:notsup
in case there is
no engine support in the underlying OpenSSL implementation.
engine_add(Engine) > Result
Engine = engine_ref()
Result = ok  {error, Reason :: term()}
Add the engine to OpenSSL's internal list.
The function raises a error:badarg
if the parameters are in wrong format.
It may also raise the exception error:notsup
in case there is
no engine support in the underlying OpenSSL implementation.
engine_remove(Engine) > Result
Engine = engine_ref()
Result = ok  {error, Reason :: term()}
Remove the engine from OpenSSL's internal list.
The function raises a error:badarg
if the parameters are in wrong format.
It may also raise the exception error:notsup
in case there is
no engine support in the underlying OpenSSL implementation.
engine_get_id(Engine) > EngineId
Engine = engine_ref()
EngineId = unicode:chardata()
Return the ID for the engine, or an empty binary if there is no id set.
The function raises a error:badarg
if the parameters are in wrong format.
It may also raise the exception error:notsup
in case there is
no engine support in the underlying OpenSSL implementation.
engine_get_name(Engine) > EngineName
Engine = engine_ref()
EngineName = unicode:chardata()
Return the name (eg a description) for the engine, or an empty binary if there is no name set.
The function raises a error:badarg
if the parameters are in wrong format.
It may also raise the exception error:notsup
in case there is
no engine support in the underlying OpenSSL implementation.
engine_list() > Result
Result = [EngineId :: unicode:chardata()]
List the id's of all engines in OpenSSL's internal list.
It may also raise the exception error:notsup
in case there is
no engine support in the underlying OpenSSL implementation.
See also the chapter Engine Load in the User's Guide.
May raise exception error:notsup
in case engine functionality is not supported by the underlying
OpenSSL implementation.
ensure_engine_loaded(EngineId, LibPath) > Result
EngineId = LibPath = unicode:chardata()
Result =
{ok, Engine :: engine_ref()}  {error, Reason :: term()}
Loads the OpenSSL engine given by EngineId
and the path to the dynamic library
implementing the engine. This function is the same as calling ensure_engine_loaded/3
with
EngineMethods
set to a list of all the possible methods. An error tuple is
returned if the engine can't be loaded.
The function raises a error:badarg
if the parameters are in wrong format.
It may also raise the exception error:notsup
in case there is
no engine support in the underlying OpenSSL implementation.
See also the chapter Engine Load in the User's Guide.
ensure_engine_loaded(EngineId, LibPath, EngineMethods) > Result
EngineId = LibPath = unicode:chardata()
EngineMethods = [engine_method_type()]
Result =
{ok, Engine :: engine_ref()}  {error, Reason :: term()}
Loads the OpenSSL engine given by EngineId
and the path to the dynamic library
implementing the engine. This function differs from the normal engine_load in that sense it
also add the engine id to the internal list in OpenSSL. Then in the following calls to the function
it just fetch the reference to the engine instead of loading it again.
An error tuple is returned if the engine can't be loaded.
The function raises a error:badarg
if the parameters are in wrong format.
It may also raise the exception error:notsup
in case there is
no engine support in the underlying OpenSSL implementation.
See also the chapter Engine Load in the User's Guide.
ensure_engine_unloaded(Engine) > Result
Engine = engine_ref()
Result = ok  {error, Reason :: term()}
Unloads an engine loaded with the ensure_engine_loaded
function.
It both removes the label from the OpenSSL internal engine list and unloads the engine.
This function is the same as calling ensure_engine_unloaded/2
with
EngineMethods
set to a list of all the possible methods. An error tuple is
returned if the engine can't be unloaded.
The function raises a error:badarg
if the parameters are in wrong format.
It may also raise the exception error:notsup
in case there is
no engine support in the underlying OpenSSL implementation.
See also the chapter Engine Load in the User's Guide.
ensure_engine_unloaded(Engine, EngineMethods) > Result
Engine = engine_ref()
EngineMethods = [engine_method_type()]
Result = ok  {error, Reason :: term()}
Unloads an engine loaded with the ensure_engine_loaded
function.
It both removes the label from the OpenSSL internal engine list and unloads the engine.
An error tuple is returned if the engine can't be unloaded.
The function raises a error:badarg
if the parameters are in wrong format.
It may also raise the exception error:notsup
in case there is
no engine support in the underlying OpenSSL implementation.
See also the chapter Engine Load in the User's Guide.
Old API
Functions
block_encrypt(Type :: block_cipher_without_iv(),
Key :: key(),
PlainText :: iodata()) >
binary()  run_time_error()
Don't use this function for new programs! Use thenewapi.
Encrypt PlainText
according to Type
block cipher.
May raise exception error:notsup
in case the chosen Type
is not supported by the underlying libcrypto implementation.
For keylengths and blocksizes see the User's Guide.
block_decrypt(Type :: block_cipher_without_iv(),
Key :: key(),
Data :: iodata()) >
binary()  run_time_error()
Don't use this function for new programs! Use the new api.
Decrypt CipherText
according to Type
block cipher.
May raise exception error:notsup
in case the chosen Type
is not supported by the underlying libcrypto implementation.
For keylengths and blocksizes see the User's Guide.
Type = block_cipher_with_iv()
AeadType = aead_cipher()
Key = key()  des3_key()
PlainText = iodata()
AAD = IVec = CipherText = CipherTag = binary()
TagLength = 1..16
Error = run_time_error()
Don't use this function for new programs! Use the new api.
Encrypt PlainText
according to Type
block cipher.
IVec
is an arbitrary initializing vector.
In AEAD (Authenticated Encryption with Associated Data) mode, encrypt
PlainText
according to Type
block cipher and calculate
CipherTag
that also authenticates the AAD
(Associated Authenticated Data).
May raise exception error:notsup
in case the chosen Type
is not supported by the underlying libcrypto implementation.
For keylengths, ivsizes and blocksizes see the User's Guide.
Type = block_cipher_with_iv()
AeadType = aead_cipher()
Key = key()  des3_key()
PlainText = iodata()
AAD = IVec = CipherText = CipherTag = binary()
Error = BadTag  run_time_error()
BadTag = error
Don't use this function for new programs! Use the new api.
Decrypt CipherText
according to Type
block cipher.
IVec
is an arbitrary initializing vector.
In AEAD (Authenticated Encryption with Associated Data) mode, decrypt
CipherText
according to Type
block cipher and check the authenticity
the PlainText
and AAD
(Associated Authenticated Data) using the
CipherTag
. May return error
if the decryption or validation fail's
May raise exception error:notsup
in case the chosen Type
is not supported by the underlying libcrypto implementation.
For keylengths, ivsizes and blocksizes see the User's Guide.
stream_init(Type, Key) > State  run_time_error()
Type = rc4
Key = iodata()
State = stream_state()
Don't use this function for new programs! Use the new api.
Initializes the state for use in RC4 stream encryption stream_encrypt and stream_decrypt
For keylengths see the User's Guide.
stream_init(Type, Key, IVec) > State  run_time_error()
Type = stream_cipher()
Key = iodata()
IVec = binary()
State = stream_state()
Don't use this function for new programs! Use the new api.
Initializes the state for use in streaming AES encryption using Counter mode (CTR).
Key
is the AES key and must be either 128, 192, or 256 bits long. IVec
is
an arbitrary initializing vector of 128 bits (16 bytes). This state is for use with
stream_encrypt and
stream_decrypt.
For keylengths and ivsizes see the User's Guide.
stream_encrypt(State, PlainText) >
{NewState, CipherText}  run_time_error()
State = stream_state()
PlainText = iodata()
NewState = stream_state()
CipherText = iodata()
Don't use this function for new programs! Use the new api.
Encrypts PlainText
according to the stream cipher Type
specified in stream_init/3.
Text
can be any number of bytes. The initial State
is created using
stream_init.
NewState
must be passed into the next call to stream_encrypt
.
stream_decrypt(State, CipherText) >
{NewState, PlainText}  run_time_error()
State = stream_state()
CipherText = iodata()
NewState = stream_state()
PlainText = iodata()
Don't use this function for new programs! Use the new api.
Decrypts CipherText
according to the stream cipher Type
specified in stream_init/3.
PlainText
can be any number of bytes. The initial State
is created using
stream_init.
NewState
must be passed into the next call to stream_decrypt
.
supports() > [Support]
Support =
{hashs, Hashs} 
{ciphers, Ciphers} 
{public_keys, PKs} 
{macs, Macs} 
{curves, Curves} 
{rsa_opts, RSAopts}Hashs =
[sha1() 
sha2() 
sha3() 
blake2() 
ripemd160 
compatibility_only_hash()]Ciphers = [cipher()]
PKs = [rsa  dss  ecdsa  dh  ecdh  ec_gf2m]
Macs = [hmac  cmac  poly1305]
Curves =
[ec_named_curve()  edwards_curve_dh()  edwards_curve_ed()]RSAopts = [rsa_sign_verify_opt()  rsa_opt()]
Don't use this function for new programs! Use supports/1 in the new api.
Can be used to determine which crypto algorithms that are supported by the underlying libcrypto library
See hash_info/1 and cipher_info/1 for information about the hash and cipher algorithms.