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added support for AES GCM decryption

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This commit is contained in:
mathewmarcus 2018-07-04 12:17:16 -05:00
parent f788c3a67a
commit 98a233fc40
1 changed files with 63 additions and 6 deletions
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69
ssl/ssl_rec.c
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@ -61,6 +61,8 @@ static char *RCSSTRING="$Id: ssl_rec.c,v 1.3 2000/11/03 06:38:06 ekr Exp $";
struct ssl_rec_decoder_ {
SSL_CipherSuite *cs;
Data *mac_key;
Data *implicit_iv; /* for AEAD ciphers */
Data *write_key; /* for AEAD ciphers */
#ifdef OPENSSL
EVP_CIPHER_CTX *evp;
#endif
@ -125,8 +127,28 @@ int ssl_create_rec_decoder(dp,cs,mk,sk,iv)
ABORT(R_NO_MEMORY);
dec->cs=cs;
if(r=r_data_create(&dec->mac_key,mk,cs->dig_len))
if(r=r_data_alloc(&dec->mac_key,cs->dig_len))
ABORT(r);
if(r=r_data_alloc(&dec->implicit_iv,cs->block))
ABORT(r);
memcpy(dec->implicit_iv->data,iv,cs->block);
if(r=r_data_create(&dec->write_key,sk,cs->eff_bits/8))
ABORT(r);
/*
This is necessary for AEAD ciphers, because we must wait to fully initialize the cipher
in order to include the implicit IV
*/
if(cs->enc==0x3b || cs->enc==0x3c){
sk=NULL;
iv=NULL;
}
else
memcpy(dec->mac_key->data,mk,cs->dig_len);
if(!(dec->evp=(EVP_CIPHER_CTX *)malloc(sizeof(EVP_CIPHER_CTX))))
ABORT(R_NO_MEMORY);
EVP_CIPHER_CTX_init(dec->evp);
@ -152,6 +174,8 @@ int ssl_destroy_rec_decoder(dp)
d=*dp;
r_data_destroy(&d->mac_key);
r_data_destroy(&d->implicit_iv);
r_data_destroy(&d->write_key);
#ifdef OPENSSL
if(d->evp){
EVP_CIPHER_CTX_cleanup(d->evp);
@ -165,6 +189,9 @@ int ssl_destroy_rec_decoder(dp)
}
#define MSB(a) ((a>>8)&0xff)
#define LSB(a) (a&0xff)
int ssl_decode_rec_data(ssl,d,ct,version,in,inl,out,outl)
ssl_obj *ssl;
ssl_rec_decoder *d;
@ -177,12 +204,44 @@ int ssl_decode_rec_data(ssl,d,ct,version,in,inl,out,outl)
{
#ifdef OPENSSL
int pad;
int r,encpadl;
UCHAR *mac,*iv;
int r,encpadl,x;
UCHAR *mac,*iv,aead_tag[13],aead_nonce[12];
CRDUMP("Ciphertext",in,inl);
if(ssl->extensions->encrypt_then_mac==2){
if(d->cs->enc==0x3b || d->cs->enc==0x3c){
memcpy(aead_nonce,d->implicit_iv->data,d->implicit_iv->len);
memcpy(aead_nonce+d->implicit_iv->len,in,12-d->implicit_iv->len);
in+=12-d->implicit_iv->len;
inl-=12-d->implicit_iv->len;
EVP_DecryptInit(d->evp,
NULL,
d->write_key->data,
aead_nonce);
EVP_CIPHER_CTX_ctrl(d->evp,EVP_CTRL_GCM_SET_TAG,16,in+(inl-16));
inl-=d->cs->eff_bits/8;
fmt_seq(d->seq,aead_tag);
d->seq++;
aead_tag[8]=ct;
aead_tag[9]=MSB(version);
aead_tag[10]=LSB(version);
aead_tag[11]=MSB(inl);
aead_tag[12]=LSB(inl);
EVP_DecryptUpdate(d->evp,NULL,outl,aead_tag,13);
EVP_DecryptUpdate(d->evp,out,outl,in,inl);
if (!(x=EVP_DecryptFinal(d->evp,NULL,&x)))
ERETURN(SSL_BAD_MAC);
}
/*
Encrypt-then-MAC is not used with AEAD ciphers, as per:
https://tools.ietf.org/html/rfc7366#section-3
*/
else if(ssl->extensions->encrypt_then_mac==2){
*outl=inl;
/* First strip off the MAC */
@ -267,8 +326,6 @@ int ssl_decode_rec_data(ssl,d,ct,version,in,inl,out,outl)
}
#define MSB(a) ((a>>8)&0xff)
#define LSB(a) (a&0xff)
#ifdef OPENSSL
/* This should go to 2^128, but we're never really going to see