static int aesni_cbc_hmac_sha1_cipher(EVP_CIPHER_CTX *ctx, unsigned char *out,
		      const unsigned char *in, size_t len)
	{
	EVP_AES_HMAC_SHA1 *key = data(ctx);
	unsigned int l;
	size_t	plen = key->payload_length,
		iv = 0,		/* explicit IV in TLS 1.1 and later */
		sha_off = 0;
#if defined(STITCHED_CALL)
	size_t	aes_off = 0,
		blocks;

	sha_off = SHA_CBLOCK-key->md.num;
#endif

	key->payload_length = NO_PAYLOAD_LENGTH;

	if (len%AES_BLOCK_SIZE) return 0;

	if (ctx->encrypt) {
		if (plen==NO_PAYLOAD_LENGTH)
			plen = len;
		else if (len!=((plen+SHA_DIGEST_LENGTH+AES_BLOCK_SIZE)&-AES_BLOCK_SIZE))
			return 0;
		else if (key->aux.tls_ver >= TLS1_1_VERSION)
			iv = AES_BLOCK_SIZE;

#if defined(STITCHED_CALL)
		if (plen>(sha_off+iv) && (blocks=(plen-(sha_off+iv))/SHA_CBLOCK)) {
			SHA1_Update(&key->md,in+iv,sha_off);

			aesni_cbc_sha1_enc(in,out,blocks,&key->ks,
				ctx->iv,&key->md,in+iv+sha_off);
			blocks *= SHA_CBLOCK;
			aes_off += blocks;
			sha_off += blocks;
			key->md.Nh += blocks>>29;
			key->md.Nl += blocks<<=3;
			if (key->md.Nl<(unsigned int)blocks) key->md.Nh++;
		} else {
			sha_off = 0;
		}
#endif
		sha_off += iv;
		SHA1_Update(&key->md,in+sha_off,plen-sha_off);

		if (plen!=len)	{	/* "TLS" mode of operation */
			if (in!=out)
				memcpy(out+aes_off,in+aes_off,plen-aes_off);

			/* calculate HMAC and append it to payload */
			SHA1_Final(out+plen,&key->md);
			key->md = key->tail;
			SHA1_Update(&key->md,out+plen,SHA_DIGEST_LENGTH);
			SHA1_Final(out+plen,&key->md);

			/* pad the payload|hmac */
			plen += SHA_DIGEST_LENGTH;
			for (l=len-plen-1;plen<len;plen++) out[plen]=l;
			/* encrypt HMAC|padding at once */
			aesni_cbc_encrypt(out+aes_off,out+aes_off,len-aes_off,
					&key->ks,ctx->iv,1);
		} else {
			aesni_cbc_encrypt(in+aes_off,out+aes_off,len-aes_off,
					&key->ks,ctx->iv,1);
		}
	} else {
		union { unsigned int  u[SHA_DIGEST_LENGTH/sizeof(unsigned int)];
			unsigned char c[SHA_DIGEST_LENGTH]; } mac;

		/* decrypt HMAC|padding at once */
		aesni_cbc_encrypt(in,out,len,
				&key->ks,ctx->iv,0);

		if (plen) {	/* "TLS" mode of operation */
			size_t inp_len, mask, j, i;
			unsigned int res, maxpad, pad, bitlen;
			int ret = 1;
			union {	unsigned int  u[SHA_LBLOCK];
				unsigned char c[SHA_CBLOCK]; }
				*data = (void *)key->md.data;

			if ((key->aux.tls_aad[plen-4]<<8|key->aux.tls_aad[plen-3])
			    >= TLS1_1_VERSION)
				iv = AES_BLOCK_SIZE;

			if (len<(iv+SHA_DIGEST_LENGTH+1))
				return 0;

			/* omit explicit iv */
			out += iv;
			len -= iv;

			/* figure out payload length */
			pad = out[len-1];
			maxpad = len-(SHA_DIGEST_LENGTH+1);
			maxpad |= (255-maxpad)>>(sizeof(maxpad)*8-8);
			maxpad &= 255;

			inp_len = len - (SHA_DIGEST_LENGTH+pad+1);
			mask = (0-((inp_len-len)>>(sizeof(inp_len)*8-1)));
			inp_len &= mask;
			ret &= (int)mask;

			key->aux.tls_aad[plen-2] = inp_len>>8;
			key->aux.tls_aad[plen-1] = inp_len;

			/* calculate HMAC */
			key->md = key->head;
			SHA1_Update(&key->md,key->aux.tls_aad,plen);

#if 1
			len -= SHA_DIGEST_LENGTH;		/* amend mac */
			if (len>=(256+SHA_CBLOCK)) {
				j = (len-(256+SHA_CBLOCK))&(0-SHA_CBLOCK);
				j += SHA_CBLOCK-key->md.num;
				SHA1_Update(&key->md,out,j);
				out += j;
				len -= j;
				inp_len -= j;
			}

			/* but pretend as if we hashed padded payload */
			bitlen = key->md.Nl+(inp_len<<3);	/* at most 18 bits */
			mac.c[0] = 0;
			mac.c[1] = (unsigned char)(bitlen>>16);
			mac.c[2] = (unsigned char)(bitlen>>8);
			mac.c[3] = (unsigned char)bitlen;
			bitlen = mac.u[0];

			mac.u[0]=0;
			mac.u[1]=0;
			mac.u[2]=0;
			mac.u[3]=0;
			mac.u[4]=0;

			for (res=key->md.num, j=0;j<len;j++) {
				size_t c = out[j];
				mask = (j-inp_len)>>(sizeof(j)*8-8);
				c &= mask;
				c |= 0x80&~mask&~((inp_len-j)>>(sizeof(j)*8-8));
				data->c[res++]=(unsigned char)c;

				if (res!=SHA_CBLOCK) continue;

				mask = 0-((inp_len+8-j)>>(sizeof(j)*8-1));
				data->u[SHA_LBLOCK-1] |= bitlen&mask;
				sha1_block_data_order(&key->md,data,1);
				mask &= 0-((j-inp_len-73)>>(sizeof(j)*8-1));
				mac.u[0] |= key->md.h0 & mask;
				mac.u[1] |= key->md.h1 & mask;
				mac.u[2] |= key->md.h2 & mask;
				mac.u[3] |= key->md.h3 & mask;
				mac.u[4] |= key->md.h4 & mask;
				res=0;
			}

			for(i=res;i<SHA_CBLOCK;i++,j++) data->c[i]=0;

			if (res>SHA_CBLOCK-8) {
				mask = 0-((inp_len+8-j)>>(sizeof(j)*8-1));
				data->u[SHA_LBLOCK-1] |= bitlen&mask;
				sha1_block_data_order(&key->md,data,1);
				mask &= 0-((j-inp_len-73)>>(sizeof(j)*8-1));
				mac.u[0] |= key->md.h0 & mask;
				mac.u[1] |= key->md.h1 & mask;
				mac.u[2] |= key->md.h2 & mask;
				mac.u[3] |= key->md.h3 & mask;
				mac.u[4] |= key->md.h4 & mask;

				memset(data,0,SHA_CBLOCK);
				j+=64;
			}
			data->u[SHA_LBLOCK-1] = bitlen;
			sha1_block_data_order(&key->md,data,1);
			mask = 0-((j-inp_len-73)>>(sizeof(j)*8-1));
			mac.u[0] |= key->md.h0 & mask;
			mac.u[1] |= key->md.h1 & mask;
			mac.u[2] |= key->md.h2 & mask;
			mac.u[3] |= key->md.h3 & mask;
			mac.u[4] |= key->md.h4 & mask;

#ifdef BSWAP
			mac.u[0] = BSWAP(mac.u[0]);
			mac.u[1] = BSWAP(mac.u[1]);
			mac.u[2] = BSWAP(mac.u[2]);
			mac.u[3] = BSWAP(mac.u[3]);
			mac.u[4] = BSWAP(mac.u[4]);
#else
			for (i=0;i<5;i++) {
				res = mac.u[i];
				mac.c[4*i+0]=(unsigned char)(res>>24);
				mac.c[4*i+1]=(unsigned char)(res>>16);
				mac.c[4*i+2]=(unsigned char)(res>>8);
				mac.c[4*i+3]=(unsigned char)res;
			}
#endif
			len += SHA_DIGEST_LENGTH;
#else
			SHA1_Update(&key->md,out,inp_len);
			res = key->md.num;
			SHA1_Final(mac.c,&key->md);

			{
			unsigned int inp_blocks, pad_blocks;

			/* but pretend as if we hashed padded payload */
			inp_blocks = 1+((SHA_CBLOCK-9-res)>>(sizeof(res)*8-1));
			res += (unsigned int)(len-inp_len);
			pad_blocks = res / SHA_CBLOCK;
			res %= SHA_CBLOCK;
			pad_blocks += 1+((SHA_CBLOCK-9-res)>>(sizeof(res)*8-1));
			for (;inp_blocks<pad_blocks;inp_blocks++)
				sha1_block_data_order(&key->md,data,1);
			}
#endif
			key->md = key->tail;
			SHA1_Update(&key->md,mac.c,SHA_DIGEST_LENGTH);
			SHA1_Final(mac.c,&key->md);

			/* verify HMAC */
			out += inp_len;
			len -= inp_len;
#if 1
			{
			unsigned char *p = out+len-1-maxpad-SHA_DIGEST_LENGTH;
			size_t off = out-p;
			unsigned int c, cmask;

			maxpad += SHA_DIGEST_LENGTH;
			for (res=0,i=0,j=0;j<maxpad;j++) {
				c = p[j];
				cmask = ((int)(j-off-SHA_DIGEST_LENGTH))>>(sizeof(int)*8-1);
				res |= (c^pad)&~cmask;	/* ... and padding */
				cmask &= ((int)(off-1-j))>>(sizeof(int)*8-1);
				res |= (c^mac.c[i])&cmask;
				i += 1&cmask;
			}
			maxpad -= SHA_DIGEST_LENGTH;

			res = 0-((0-res)>>(sizeof(res)*8-1));
			ret &= (int)~res;
			}
#else
			for (res=0,i=0;i<SHA_DIGEST_LENGTH;i++)
				res |= out[i]^mac.c[i];
			res = 0-((0-res)>>(sizeof(res)*8-1));
			ret &= (int)~res;

			/* verify padding */
			pad = (pad&~res) | (maxpad&res);
			out = out+len-1-pad;
			for (res=0,i=0;i<pad;i++)
				res |= out[i]^pad;

			res = (0-res)>>(sizeof(res)*8-1);
			ret &= (int)~res;
#endif
			return ret;
		} else {
			SHA1_Update(&key->md,out,len);
		}
	}

	return 1;
	}
This weakness pertains to the use of cryptographic functions that are weak, misconfigured, or outdated, which undermines the intended protection of encrypted data and communications.