HMAC: function()

in src/ecdh.js [317:369]

• 38 lines of code
• 10 McCabe index (conditional complexity)

        HMAC: function(sha, M, K, tag) {
            /* Input is from an octet m        *
             * olen is requested output length in bytes. k is the key  *
             * The output is the calculated tag */
            var olen = tag.length,
                B = [],
                b = 64,
                K0, i;

            if (sha > 32) {
                b = 128;
            }

            K0 = new Array(b);

            //b=K0.length;
            if (olen < 4) {
                return 0;
            }

            for (i = 0; i < b; i++) {
                K0[i] = 0;
            }

            if (K.length > b) {
                B = this.hashit(sha, K, 0, null, 0);
                for (i = 0; i < sha; i++) {
                    K0[i] = B[i];
                }
            } else {
                for (i = 0; i < K.length; i++) {
                    K0[i] = K[i];
                }
            }

            for (i = 0; i < b; i++) {
                K0[i] ^= 0x36;
            }

            B = this.hashit(sha, K0, 0, M, 0);

            for (i = 0; i < b; i++) {
                K0[i] ^= 0x6a;
            }

            B = this.hashit(sha, K0, 0, B, olen);

            for (i = 0; i < olen; i++) {
                tag[i] = B[i];
            }

            return 1;
        },