From 68e803093b8bf43b39f3090a1b717b850a5e8f4b Mon Sep 17 00:00:00 2001 From: Sverker Eriksson Date: Mon, 24 Oct 2011 15:01:28 +0200 Subject: Clean up of public_key code adding specs and documentation --- lib/public_key/src/pubkey_pbe.erl | 57 ++++++++++++++++++++++----------------- 1 file changed, 33 insertions(+), 24 deletions(-) (limited to 'lib/public_key/src/pubkey_pbe.erl') diff --git a/lib/public_key/src/pubkey_pbe.erl b/lib/public_key/src/pubkey_pbe.erl index 32be347039..77d6943d96 100644 --- a/lib/public_key/src/pubkey_pbe.erl +++ b/lib/public_key/src/pubkey_pbe.erl @@ -26,7 +26,6 @@ -export([pbdkdf1/4, pbdkdf2/6]). -define(DEFAULT_SHA_MAC_KEYLEN, 20). - -define(ASN1_OCTET_STR_TAG, 4). -define(IV_LEN, 8). @@ -34,11 +33,11 @@ %% Internal application API %%==================================================================== -pbdkdf2(Password, Salt, Count, DerivedKeyLen, Prf, PrfOutputLen)-> - NumBlocks = ceiling(DerivedKeyLen / PrfOutputLen), - NumLastBlockOctets = DerivedKeyLen - (NumBlocks - 1) * PrfOutputLen , - blocks(NumBlocks, NumLastBlockOctets, 1, Password, Salt, Count, Prf, PrfOutputLen, <<>>). - +%%-------------------------------------------------------------------- +-spec encode(binary(), string(), string(), term()) -> binary(). +%% +%% Description: Performs password based encoding +%%-------------------------------------------------------------------- encode(Data, Password, "DES-CBC" = Cipher, KeyDevParams) -> {Key, IV} = password_to_key_and_iv(Password, Cipher, KeyDevParams), crypto:des_cbc_encrypt(Key, IV, Data); @@ -51,7 +50,11 @@ encode(Data, Password, "DES-EDE3-CBC" = Cipher, KeyDevParams) -> encode(Data, Password, "RC2-CBC" = Cipher, KeyDevParams) -> {Key, IV} = password_to_key_and_iv(Password, Cipher, KeyDevParams), crypto:rc2_cbc_encrypt(Key, IV, Data). - +%%-------------------------------------------------------------------- +-spec decode(binary(), string(), string(), term()) -> binary(). +%% +%% Description: Performs password based decoding +%%-------------------------------------------------------------------- decode(Data, Password,"DES-CBC"= Cipher, KeyDevParams) -> {Key, IV} = password_to_key_and_iv(Password, Cipher, KeyDevParams), crypto:des_cbc_decrypt(Key, IV, Data); @@ -102,7 +105,13 @@ decrypt_parameters(#'EncryptedPrivateKeyInfo_encryptionAlgorithm'{ %%-------------------------------------------------------------------- %%% Internal functions %%-------------------------------------------------------------------- -password_to_key_and_iv(Password, Cipher, {salt, Salt}) -> +password_to_key_and_iv(Password, _, #'PBES2-params'{} = Params) -> + {Salt, ItrCount, KeyLen, PseudoRandomFunction, PseudoOtputLen, IV} = + key_derivation_params(Params), + <> = + pbdkdf2(Password, Salt, ItrCount, KeyLen, PseudoRandomFunction, PseudoOtputLen), + {Key, IV}; +password_to_key_and_iv(Password, Cipher, Salt) -> KeyLen = derived_key_length(Cipher, undefined), <> = pem_encrypt(<<>>, Password, Salt, ceiling(KeyLen div 16), <<>>, md5), @@ -110,12 +119,6 @@ password_to_key_and_iv(Password, Cipher, {salt, Salt}) -> %% pbdkdf1 and uses then salt as IV {Key, Salt}. -password_to_key_and_iv(Password, _, #'PBES2-params'{} = Params) -> - {Salt, ItrCount, KeyLen, PseudoRandomFunction, PseudoOtputLen, IV} = - key_derivation_params(Params), - <> = - pbdkdf2(Password, Salt, ItrCount, KeyLen, PseudoRandomFunction, PseudoOtputLen), - {Key, IV}. pem_encrypt(_, _, _, 0, Acc, _) -> Acc; pem_encrypt(Prev, Password, Salt, Count, Acc, Hash) -> @@ -129,8 +132,8 @@ do_pbdkdf1(Prev, Count, Acc, Hash) -> do_pbdkdf1(Result, Count-1 , <>, Hash). iv(#'PBES2-params_encryptionScheme'{algorithm = Algo, - parameters = ASNIV}) when (Algo == ?'desCBC') or - (Algo == ?'des-EDE3-CBC') -> + parameters = ASNIV}) when (Algo == ?'desCBC') or + (Algo == ?'des-EDE3-CBC') -> %% This is an so called open ASN1-type that in this %% case will be an octet-string of length 8 <> = ASNIV, @@ -145,7 +148,8 @@ blocks(1, N, Index, Password, Salt, Count, Prf, PrfLen, Acc) -> <>; blocks(NumBlocks, N, Index, Password, Salt, Count, Prf, PrfLen, Acc) -> XorSum = xor_sum(Password, Salt, Count, Index, Prf, PrfLen), - blocks(NumBlocks -1, N, Index +1, Password, Salt, Count, Prf, PrfLen, <>). + blocks(NumBlocks -1, N, Index +1, Password, Salt, Count, Prf, + PrfLen, <>). xor_sum(Password, Salt, Count, Index, Prf, PrfLen) -> Result = Prf(Password, [Salt,<>], PrfLen), @@ -172,11 +176,13 @@ key_derivation_params(#'PBES2-params'{keyDerivationFunc = KeyDerivationFunc, #'PBES2-params_encryptionScheme'{algorithm = Algo} = EncScheme, {PseudoRandomFunction, PseudoOtputLen} = pseudo_random_function(Prf), KeyLen = derived_key_length(Algo, Length), - {iolist_to_binary(OctetSalt), Count, KeyLen, PseudoRandomFunction, PseudoOtputLen, iv(EncScheme)}. + {OctetSalt, Count, KeyLen, + PseudoRandomFunction, PseudoOtputLen, iv(EncScheme)}. -%% This function currently matches a tuple that ougth to be the value ?'id-hmacWithSHA1, -%% but we need some kind of ASN1-fix for this. -pseudo_random_function(#'PBKDF2-params_prf'{algorithm = {_,_, _,'id-hmacWithSHA1'}}) -> +%% This function currently matches a tuple that ougth to be the value +%% ?'id-hmacWithSHA1, but we need some kind of ASN1-fix for this. +pseudo_random_function(#'PBKDF2-params_prf'{algorithm = + {_,_, _,'id-hmacWithSHA1'}}) -> {fun crypto:sha_mac/3, pseudo_output_length(?'id-hmacWithSHA1')}. pseudo_output_length(?'id-hmacWithSHA1') -> @@ -184,11 +190,14 @@ pseudo_output_length(?'id-hmacWithSHA1') -> derived_key_length(_, Len) when is_integer(Len) -> Len; -derived_key_length(Cipher,_) when (Cipher == ?'desCBC') or (Cipher == "DES-CBC") -> +derived_key_length(Cipher,_) when (Cipher == ?'desCBC') or + (Cipher == "DES-CBC") -> 8; -derived_key_length(Cipher,_) when (Cipher == ?'rc2CBC') or (Cipher == "RC2-CBC") -> +derived_key_length(Cipher,_) when (Cipher == ?'rc2CBC') or + (Cipher == "RC2-CBC") -> 16; -derived_key_length(Cipher,_) when (Cipher == ?'des-EDE3-CBC') or (Cipher == "DES-EDE3-CBC") -> +derived_key_length(Cipher,_) when (Cipher == ?'des-EDE3-CBC') or + (Cipher == "DES-EDE3-CBC") -> 24. cipher(#'PBES2-params_encryptionScheme'{algorithm = ?'desCBC'}) -> -- cgit v1.2.3