From 03e06fd43aff73b4a5c9d367968a1279371ae252 Mon Sep 17 00:00:00 2001 From: Guus Sliepen Date: Sun, 18 Mar 2012 16:41:13 +0100 Subject: [PATCH] Allow CTR mode counter to be set to a specific value. --- src/openssl/cipher.c | 13 +++++++++++++ src/openssl/cipher.h | 1 + 2 files changed, 14 insertions(+) diff --git a/src/openssl/cipher.c b/src/openssl/cipher.c index 9b9e3446..1ca15abb 100644 --- a/src/openssl/cipher.c +++ b/src/openssl/cipher.c @@ -105,6 +105,19 @@ bool cipher_set_key_from_rsa(cipher_t *cipher, void *key, size_t len, bool encry return false; } +bool cipher_set_counter(cipher_t *cipher, const void *counter, size_t len) { + if(len > cipher->cipher->block_size - 4) { + logger(DEBUG_ALWAYS, LOG_ERR, "Counter too long"); + abort(); + } + + memcpy(cipher->counter->counter + cipher->cipher->block_size - len, counter, len); + memset(cipher->counter->counter, 0, 4); + cipher->counter->n = 0; + + return true; +} + bool cipher_set_counter_key(cipher_t *cipher, void *key) { int result = EVP_EncryptInit_ex(&cipher->ctx, cipher->cipher, NULL, (unsigned char *)key, NULL); if(!result) { diff --git a/src/openssl/cipher.h b/src/openssl/cipher.h index 589ec4c4..9b6221bc 100644 --- a/src/openssl/cipher.h +++ b/src/openssl/cipher.h @@ -39,6 +39,7 @@ extern void cipher_close(cipher_t *); extern size_t cipher_keylength(const cipher_t *); extern bool cipher_set_key(cipher_t *, void *, bool); extern bool cipher_set_key_from_rsa(cipher_t *, void *, size_t, bool); +extern bool cipher_set_counter(cipher_t *, const void *, size_t); extern bool cipher_set_counter_key(cipher_t *, void *); extern bool cipher_encrypt(cipher_t *, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool); extern bool cipher_decrypt(cipher_t *, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool); -- 2.20.1