crypto
Crypto Functions
This module provides a set of cryptographic functions.
-
Hash functions -
Secure Hash Standard ,The MD5 Message Digest Algorithm (RFC 1321) andThe MD4 Message Digest Algorithm (RFC 1320) -
Hmac functions -
Keyed-Hashing for Message Authentication (RFC 2104) -
Block ciphers -
ECB, CBC, CFB, OFB and CTR -
RSA encryption RFC 1321 -
Digital signatures
Digital Signature Standard (DSS) andElliptic Curve Digital Signature Algorithm (ECDSA) -
Secure Remote Password Protocol (SRP - RFC 2945)
DATA TYPES
key_value() = integer() | binary()
Always binary()
when used as return value
rsa_public() = [key_value()] = [E, N]
Where E is the public exponent and N is public modulus.
rsa_private() = [key_value()] = [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_value()] = [P, Q, G, Y]
Where P, Q and G are the dss parameters and Y is the public key.
dss_private() = [key_value()] = [P, Q, G, X]
Where P, Q and G are the dss parameters and X is the private key.
srp_public() = key_value()
Where is A
or B
from
srp_private() = key_value()
Where is a
or b
from
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
dh_public() = key_value()
dh_private() = key_value()
dh_params() = [key_value()] = [P, G]
ecdh_public() = key_value()
ecdh_private() = key_value()
ecdh_params() = ec_named_curve() |
{ec_field(), Prime :: key_value(), Point :: key_value(), Order :: integer(), CoFactor :: none | integer()}
ec_field() = {prime_field, Prime :: integer()} |
{characteristic_two_field, M :: integer(), Basis :: ec_basis()}
ec_basis() = {tpbasis, K :: non_neg_integer()} |
{ppbasis, K1 :: non_neg_integer(), K2 :: non_neg_integer(), K3 :: non_neg_integer()} |
onbasis
ec_named_curve() ->
sect571r1| sect571k1| sect409r1| sect409k1| secp521r1| secp384r1| secp224r1| secp224k1|
secp192k1| secp160r2| secp128r2| secp128r1| sect233r1| sect233k1| sect193r2| sect193r1|
sect131r2| sect131r1| sect283r1| sect283k1| sect163r2| secp256k1| secp160k1| secp160r1|
secp112r2| secp112r1| sect113r2| sect113r1| sect239k1| sect163r1| sect163k1| secp256r1|
secp192r1
stream_cipher() = rc4 | aes_ctr
block_cipher() = aes_cbc128 | aes_cfb128 | blowfish_cbc |
blowfish_cfb64 | des_cbc | des_cfb | des3_cbc | des3_cbf
| des_ede3 | rc2_cbc
stream_key() = aes_key() | rc4_key()
block_key() = aes_key() | blowfish_key() | des_key()| des3_key()
aes_key() = iodata()
Key length is 128, 192 or 256 bits
rc4_key() = iodata()
Variable key length from 8 bits up to 2048 bits (usually between 40 and 256)
blowfish_key() = iodata()
Variable key length from 32 bits up to 448 bits
des_key() = iodata()
Key length is 64 bits (in CBC mode only 8 bits are used)
des3_key() = [binary(), binary(), binary()]
Each key part is 64 bits (in CBC mode only 8 bits are used)
digest_type() = md5 | sha | sha224 | sha256 | sha384 | sha512
hash_algorithms() = md5 | ripemd160 | sha | sha224 | sha256 | sha384 | sha512
md4 is also supported for hash_init/1 and hash/2.
Note that both md4 and md5 are recommended only for compatibility with existing applications.
cipher_algorithms() = des_cbc | des_cfb | des3_cbc | des3_cbf | des_ede3 |
blowfish_cbc | blowfish_cfb64 | aes_cbc128 | aes_cfb128| aes_cbc256 | rc2_cbc | aes_ctr| rc4
public_key_algorithms() = rsa |dss | ecdsa | dh | ecdh
Functions
block_encrypt(Type, Key, Ivec, PlainText) -> CipherText
Type = block_cipher()
Key = block_key()
PlainText = iodata()
IVec = CipherText = binary()
Encrypt PlainText
according to Type
block cipher.
IVec
is an arbitrary initializing vector.
block_decrypt(Type, Key, Ivec, CipherText) -> PlainText
Type = block_cipher()
Key = block_key()
PlainText = iodata()
IVec = CipherText = binary()
Decrypt CipherText
according to Type
block cipher.
IVec
is an arbitrary initializing vector.
bytes_to_integer(Bin) -> Integer
Bin = binary() - as returned by crypto functions
Integer = integer()
Convert binary representation, of an integer, to an Erlang integer.
compute_key(Type, OthersPublicKey, MyKey, Params) -> SharedSecret
Type = dh | ecdh | srp
OthersPublicKey = dh_public() | ecdh_public() | srp_public()
MyKey = dh_private() | ecdh_private() | {srp_public(),srp_private()}
Params = dh_params() | ecdh_params() | SrpUserParams | SrpHostParams
SrpUserParams = {user, [DerivedKey::binary(), Prime::binary(), Generator::binary(), Version::atom() | [Scrambler:binary()]]}
SrpHostParams = {host, [Verifier::binary(), Prime::binary(), Version::atom() | [Scrambler::binary]]}
SharedSecret = binary()
Computes the shared secret from the private key and the other party's public key. See also public_key:compute_key/2
exor(Data1, Data2) -> Result
Data1, Data2 = iodata()
Result = binary()
Performs bit-wise XOR (exclusive or) on the data supplied.
generate_key(Type, Params) -> {PublicKey, PrivKeyOut}
generate_key(Type, Params, PrivKeyIn) -> {PublicKey, PrivKeyOut}
Type = dh | ecdh | srp
Params = dh_params() | ecdh_params() | SrpUserParams | SrpHostParams
SrpUserParams = {user, [Generator::binary(), Prime::binary(), Version::atom()]}
SrpHostParams = {host, [Verifier::binary(), Generator::binary(), Prime::binary(), Version::atom()]}
PublicKey = dh_public() | ecdh_public() | srp_public()
PrivKeyIn = undefined | dh_private() | srp_private()
PrivKeyOut = dh_private() | ecdh_private() | srp_private()
Generates public keys of type Type
.
See also public_key:generate_key/1
hash(Type, Data) -> Digest
Type = md4 | hash_algorithms()
Data = iodata()
Digest = binary()
Computes a message digest of type Type
from Data
.
May throw exception notsup
in case the chosen Type
is not supported by the underlying OpenSSL implementation.
hash_init(Type) -> Context
Type = md4 | hash_algorithms()
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 throw exception notsup
in case the chosen Type
is not supported by the underlying OpenSSL implementation.
hash_update(Context, Data) -> NewContext
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(Context) -> Digest
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
hmac(Type, Key, Data, MacLength) -> Mac
Type = hash_algorithms() - except ripemd160
Key = iodata()
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) -> Context
Type = hash_algorithms() - except ripemd160
Key = iodata()
Context = binary()
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(Context, Data) -> NewContext
Context = NewContext = binary()
Data = iodata()
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
hmac_final(Context) -> Mac
Context = 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(Context, HashLen) -> Mac
Context = Mac = binary()
HashLen = non_neg_integer()
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.
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">>,9469983,<<"OpenSSL 0.9.8a 11 Oct 2005">>}]
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 OpenSSL library used at runtime.
In earlier OTP versions both numeric and text was taken from the library.
mod_pow(N, P, M) -> Result
N, P, M = binary() | integer()
Result = binary() | error
Computes the function N^P mod M
.
next_iv(Type, Data) -> NextIVec
next_iv(Type, Data, IVec) -> NextIVec
Type = des_cbc | des3_cbc | aes_cbc | des_cfb
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.
private_decrypt(Type, ChipherText, PrivateKey, Padding) -> PlainText
Type = rsa
ChipherText = binary()
PrivateKey = rsa_private()
Padding = rsa_pkcs1_padding | rsa_pkcs1_oaep_padding | rsa_no_padding
PlainText = binary()
Decrypts the ChipherText
, 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(Type, PlainText, PrivateKey, Padding) -> ChipherText
Type = rsa
PlainText = binary()
PrivateKey = rsa_private()
Padding = rsa_pkcs1_padding | rsa_no_padding
ChipherText = binary()
PlainText
must be less
than byte_size(N)-11
if rsa_pkcs1_padding
is
used, and byte_size(N)
if rsa_no_padding
is
used, where N is public modulus of the RSA key.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(Type, ChipherText, PublicKey, Padding) -> PlainText
Type = rsa
ChipherText = binary()
PublicKey = rsa_public()
Padding = rsa_pkcs1_padding | rsa_no_padding
PlainText = binary()
Decrypts the ChipherText
, 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(Type, PlainText, PublicKey, Padding) -> ChipherText
Type = rsa
PlainText = binary()
PublicKey = rsa_public()
Padding = rsa_pkcs1_padding | rsa_pkcs1_oaep_padding | rsa_no_padding
ChipherText = binary()
PlainText
must be less
than byte_size(N)-11
if rsa_pkcs1_padding
is
used, and byte_size(N)
if rsa_no_padding
is
used, where N is public modulus of the RSA key.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_bytes(N) -> binary()
N = integer()
Generates N bytes randomly uniform 0..255, and returns the
result in a binary. Uses the crypto
library pseudo-random
number generator.
rand_uniform(Lo, Hi) -> N
Lo, Hi, N = integer()
Generate a random number N, Lo =< N < Hi.
Uses the
crypto
library pseudo-random number generator.
Hi
must be larger than Lo
.
sign(Algorithm, DigestType, Msg, Key) -> binary()
Algorithm = rsa | dss | ecdsa
Msg = binary() | {digest,binary()}
DigestType = digest_type()
Key = rsa_private() | dss_private() | [ecdh_private(),ecdh_params()]
Creates a digital signature.
Algorithm dss
can only be used together with digest type
sha
.
start() -> ok
Equivalent to application:start(crypto).
stop() -> ok
Equivalent to application:stop(crypto).
strong_rand_bytes(N) -> binary()
N = integer()
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 throw exception low_entropy
in case the random generator
failed due to lack of secure "randomness".
stream_init(Type, Key) -> State
Type = rc4
State = opaque()
Key = iodata()
Initializes the state for use in RC4 stream encryption stream_encrypt and stream_decrypt
stream_init(Type, Key, IVec) -> State
Type = aes_ctr
State = opaque()
Key = iodata()
IVec = binary()
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 bts long. IVec
is
an arbitrary initializing vector of 128 bits (16 bytes). This state is for use with
stream_encrypt and
stream_decrypt.
stream_encrypt(State, PlainText) -> { NewState, CipherText}
Text = iodata()
CipherText = binary()
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 }
CipherText = iodata()
PlainText = binary()
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_encrypt
.
supports() -> AlgorithmList
AlgorithmList = [{hashs, [hash_algorithms()]}, {ciphers, [cipher_algorithms()]}, {public_keys, [public_key_algorithms()]}
Can be used to determine which crypto algorithms that are supported by the underlying OpenSSL library
verify(Algorithm, DigestType, Msg, Signature, Key) -> boolean()
Algorithm = rsa | dss | ecdsa
Msg = binary() | {digest,binary()}
DigestType = digest_type()
Signature = binary()
Key = rsa_public() | dss_public() | [ecdh_public(),ecdh_params()]
Verifies a digital signature
Algorithm dss
can only be used together with digest type
sha
.