From 111642369ba778d5b8d18f1a9d8acf379ab45c13 Mon Sep 17 00:00:00 2001 From: Benedict Date: Sat, 3 Sep 2016 00:12:20 +0200 Subject: set4, completed challend 28 --- lib/lib4.c | 42 ++++++++++++++++++++++++++++++++++++++++-- lib/lib4.h | 3 +++ 2 files changed, 43 insertions(+), 2 deletions(-) (limited to 'lib') diff --git a/lib/lib4.c b/lib/lib4.c index 5b7ec7d..1b25ef9 100644 --- a/lib/lib4.c +++ b/lib/lib4.c @@ -21,8 +21,9 @@ int aes_ctr_edit(char *ciphertext, int ciphertext_length, int offset, char *newt return 0; } -void sha1_hmac(unsigned int *mac, unsigned char *message, unsigned int msg_len, unsigned char *key, - unsigned int key_len) + +void sha1_hmac(unsigned int *mac, unsigned char *message, unsigned int msg_len, + unsigned char *key, unsigned int key_len) { char *res = malloc(msg_len + key_len); @@ -32,6 +33,7 @@ void sha1_hmac(unsigned int *mac, unsigned char *message, unsigned int msg_len, SHA1Context sh; SHA1Reset(&sh); + SHA1Input(&sh, res, (msg_len + key_len)); SHA1Result(&sh); @@ -48,3 +50,39 @@ int sha1_hmac_verify(unsigned int *mac, unsigned char *msg, unsigned int msg_len return !memcmp(com_mac, mac, 20); } + +int sha1_padding(unsigned long msg_len, char **result) +{ + int i; + unsigned int padding_len = 64 - (msg_len % 64); + // enough sapce for the length of the message? + padding_len = padding_len < 9 ? padding_len+64 : padding_len; + + (*result) = malloc(padding_len); + + memset((*result), 0x00, padding_len); + // append 1 + memset(&(*result)[0], 0x80, 1); + //(*result)[0] = 0x80; + + // write the 8 byte msg_len at the end bytewise + for(i=0;i<8;i++) { + (*result)[padding_len-i-1] = (msg_len*8 >> (i*8)) & 0xFF; + } + + return padding_len; +} + +void sha1_hmac_forge(unsigned int *mac, unsigned char *text, unsigned int text_len, + unsigned int *sha1_registers) +{ + SHA1Context sh; + SHA1Reset(&sh); + + sha1_set_magic_nr(&sh, sha1_registers); + + SHA1Input(&sh, text, text_len); + SHA1Result(&sh); + + memcpy(mac, &(sh.Message_Digest), 20); +} diff --git a/lib/lib4.h b/lib/lib4.h index 1d7bd36..08ecbcc 100644 --- a/lib/lib4.h +++ b/lib/lib4.h @@ -10,4 +10,7 @@ void sha1_hmac(unsigned int *mac, unsigned char *message, unsigned int msg_len, unsigned int key_len); int sha1_hmac_verify(unsigned int *mac, unsigned char *msg, unsigned int msg_len, unsigned char *key, unsigned int key_len); +int sha1_padding(unsigned long msg_len, char **result); +void sha1_hmac_forge(unsigned int *mac, unsigned char *text, unsigned int text_len, + unsigned int *sha1_registers); #endif -- cgit v1.2.3-70-g09d2