BOOL gcm_add_cipher(gcm *g,int mode,char *plain,int len,char *cipher)
{ /* Add plaintext to extract ciphertext, or visa versa, depending on mode. len is length of plaintext/ciphertext. Note this file combines GHASH() functionality with encryption/decryption */
int i,j=0;
MR_WORD counter;
MR_BYTE B[16];
if (g->status==GCM_ACCEPTING_HEADER) g->status=GCM_ACCEPTING_CIPHER;
if (g->status!=GCM_ACCEPTING_CIPHER) return FALSE;
while (j<len)
{
if (cipher!=NULL)
{
counter=pack((MR_BYTE *)&(g->a.f[12]));
counter++;
unpack(counter,(MR_BYTE *)&(g->a.f[12])); /* increment counter */
for (i=0;i<16;i++) B[i]=g->a.f[i];
aes_ecb_encrypt(&(g->a),B); /* encrypt it */
}
for (i=0;i<16 && j<len;i++)
{
if (cipher==NULL)
g->stateX[i]^=plain[j++];
else
{
if (mode==GCM_ENCRYPTING) cipher[j]=plain[j]^B[i];
if (mode==GCM_DECRYPTING) plain[j]=cipher[j]^B[i];
g->stateX[i]^=cipher[j++];
}
g->lenC[1]++; if (g->lenC[1]==0) g->lenC[0]++;
}
gf2mul(g);
}
if (len%16!=0) g->status=GCM_NOT_ACCEPTING_MORE;
return TRUE;
}
/* Add Ciphertext - decrypts to plaintext */
int MCL_GCM_add_cipher(mcl_gcm *g,char *plain,char *cipher,int len)
{ /* Add ciphertext to extract plaintext, len is length of ciphertext. */
int i,j=0;
unsign32 counter;
uchar B[16];
if (g->status==MCL_GCM_ACCEPTING_HEADER) g->status=MCL_GCM_ACCEPTING_CIPHER;
if (g->status!=MCL_GCM_ACCEPTING_CIPHER) return 0;
while (j<len)
{
counter=pack((uchar *)&(g->a.f[12]));
counter++;
unpack(counter,(uchar *)&(g->a.f[12])); /* increment counter */
for (i=0;i<16;i++) B[i]=g->a.f[i];
MCL_AES_ecb_encrypt(&(g->a),B); /* encrypt it */
for (i=0;i<16 && j<len;i++)
{
plain[j]=cipher[j]^B[i];
g->stateX[i]^=cipher[j++];
g->lenC[1]++; if (g->lenC[1]==0) g->lenC[0]++;
}
gf2mul(g);
}
if (len%16!=0) g->status=MCL_GCM_NOT_ACCEPTING_MORE;
return 1;
}
void gcm_finish(gcm *g,char *tag)
{ /* Finish off and extract tag (MAC) */
int i,j;
MR_WORD F[4];
MR_BYTE L[16];
/* convert lengths from bytes to bits */
F[0]=(g->lenA[0]<<3)|(g->lenA[1]&0xE0000000)>>29;
F[1]=g->lenA[1]<<3;
F[2]=(g->lenC[0]<<3)|(g->lenC[1]&0xE0000000)>>29;
F[3]=g->lenC[1]<<3;
for (i=j=0;i<NB;i++,j+=4) unpack(F[i],(MR_BYTE *)&L[j]);
for (i=0;i<16;i++) g->stateX[i]^=L[i];
gf2mul(g);
g->counter=1;
unpack(g->counter,(MR_BYTE *)&(g->a.f[12])); /* reset counter */
for (i=0;i<16;i++) L[i]=g->a.f[i];
aes_ecb_encrypt(&(g->a),L); /* E(K,Y0) */
for (i=0;i<16;i++) L[i]^=g->stateX[i];
g->status=GCM_FINISHED;
for (i=0;i<16;i++) tag[i]=L[i];
aes_end(&(g->a));
}
BOOL gcm_add_cipher(gcm *g,int mode,char *plain,int len,char *cipher)
{ /* Add plaintext to extract ciphertext, or visa versa, depending on mode. len is length of plaintext/ciphertext */
int i,j=0;
MR_BYTE B[16];
if (g->status==GCM_ACCEPTING_HEADER) g->status=GCM_ACCEPTING_CIPHER;
if (g->status!=GCM_ACCEPTING_CIPHER) return FALSE;
while (j<len)
{
g->counter++;
unpack(g->counter,(MR_BYTE *)&(g->a.f[12])); /* get counter */
for (i=0;i<16;i++) B[i]=g->a.f[i];
aes_ecb_encrypt(&(g->a),B); /* encrypt it */
for (i=0;i<16 && j<len;i++)
{
if (mode==GCM_ENCRYPTING) cipher[j]=plain[j]^B[i];
if (mode==GCM_DECRYPTING) plain[j]=cipher[j]^B[i];
g->stateX[i]^=cipher[j++];
g->lenC[1]++; if (g->lenC[1]==0) g->lenC[0]++;
}
gf2mul(g);
}
if (len%16!=0) g->status=GCM_NOT_ACCEPTING_MORE;
return TRUE;
}
/* SU= 32 */
static void MCL_GCM_wrap(mcl_gcm *g)
{ /* Finish off GMCL_HASH */
int i,j;
unsign32 F[4];
uchar L[16];
/* convert lengths from bytes to bits */
F[0]=(g->lenA[0]<<3)|(g->lenA[1]&0xE0000000)>>29;
F[1]=g->lenA[1]<<3;
F[2]=(g->lenC[0]<<3)|(g->lenC[1]&0xE0000000)>>29;
F[3]=g->lenC[1]<<3;
for (i=j=0;i<NB;i++,j+=4) unpack(F[i],(uchar *)&L[j]);
for (i=0;i<16;i++) g->stateX[i]^=L[i];
gf2mul(g);
}
static void gcm_wrap(gcm *g)
{ /* Finish off GHASH */
int i,j;
MR_WORD F[4];
MR_BYTE L[16];
/* convert lengths from bytes to bits */
F[0]=(g->lenA[0]<<3)|(g->lenA[1]&0xE0000000)>>29;
F[1]=g->lenA[1]<<3;
F[2]=(g->lenC[0]<<3)|(g->lenC[1]&0xE0000000)>>29;
F[3]=g->lenC[1]<<3;
for (i=j=0;i<NB;i++,j+=4) unpack(F[i],(MR_BYTE *)&L[j]);
for (i=0;i<16;i++) g->stateX[i]^=L[i];
gf2mul(g);
}
/* Add Header data - included but not encrypted */
int MCL_GCM_add_header(mcl_gcm* g,char *header,int len)
{ /* Add some header. Won't be encrypted, but will be authenticated. len is length of header */
int i,j=0;
if (g->status!=MCL_GCM_ACCEPTING_HEADER) return 0;
while (j<len)
{
for (i=0;i<16 && j<len;i++)
{
g->stateX[i]^=header[j++];
g->lenA[1]++; if (g->lenA[1]==0) g->lenA[0]++;
}
gf2mul(g);
}
if (len%16!=0) g->status=MCL_GCM_ACCEPTING_CIPHER;
return 1;
}
static int MCL_GCM_ghash(mcl_gcm *g,char *plain,int len)
{
int i,j=0;
if (g->status==MCL_GCM_ACCEPTING_HEADER) g->status=MCL_GCM_ACCEPTING_CIPHER;
if (g->status!=MCL_GCM_ACCEPTING_CIPHER) return 0;
while (j<len)
{
for (i=0;i<16 && j<len;i++)
{
g->stateX[i]^=plain[j++];
g->lenC[1]++; if (g->lenC[1]==0) g->lenC[0]++;
}
gf2mul(g);
}
if (len%16!=0) g->status=MCL_GCM_NOT_ACCEPTING_MORE;
return 1;
}
static int GCM_ghash(gcm *g,char *plain,int len)
{
int i,j=0;
unsign32 counter;
uchar B[16];
if (g->status==GCM_ACCEPTING_HEADER) g->status=GCM_ACCEPTING_CIPHER;
if (g->status!=GCM_ACCEPTING_CIPHER) return 0;
while (j<len)
{
for (i=0;i<16 && j<len;i++)
{
g->stateX[i]^=plain[j++];
g->lenC[1]++; if (g->lenC[1]==0) g->lenC[0]++;
}
gf2mul(g);
}
if (len%16!=0) g->status=GCM_NOT_ACCEPTING_MORE;
return 1;
}
