There's no native MD5 functionality in JavaScript, but Joseph Meyers has written his own function, which accoring to this stackoverflow thread is the fastest one in town!

It didn't take much work, but I've converted it into a utility class, ready to drop into your Sencha Touch projects.

Ext.define('MyApp.util.Crypto', {
singleton : true,
alternateClassName : ['Crypto'],
constructor: function(config) {
this.initConfig(config);
},
md5cycle: function(x, k) {
var me = this;
var a = x[0], b = x[1], c = x[2], d = x[3];
a = me.ff(a, b, c, d, k[0], 7, -680876936);
d = me.ff(d, a, b, c, k[1], 12, -389564586);
c = me.ff(c, d, a, b, k[2], 17, 606105819);
b = me.ff(b, c, d, a, k[3], 22, -1044525330);
a = me.ff(a, b, c, d, k[4], 7, -176418897);
d = me.ff(d, a, b, c, k[5], 12, 1200080426);
c = me.ff(c, d, a, b, k[6], 17, -1473231341);
b = me.ff(b, c, d, a, k[7], 22, -45705983);
a = me.ff(a, b, c, d, k[8], 7, 1770035416);
d = me.ff(d, a, b, c, k[9], 12, -1958414417);
c = me.ff(c, d, a, b, k[10], 17, -42063);
b = me.ff(b, c, d, a, k[11], 22, -1990404162);
a = me.ff(a, b, c, d, k[12], 7, 1804603682);
d = me.ff(d, a, b, c, k[13], 12, -40341101);
c = me.ff(c, d, a, b, k[14], 17, -1502002290);
b = me.ff(b, c, d, a, k[15], 22, 1236535329);
a = me.gg(a, b, c, d, k[1], 5, -165796510);
d = me.gg(d, a, b, c, k[6], 9, -1069501632);
c = me.gg(c, d, a, b, k[11], 14, 643717713);
b = me.gg(b, c, d, a, k[0], 20, -373897302);
a = me.gg(a, b, c, d, k[5], 5, -701558691);
d = me.gg(d, a, b, c, k[10], 9, 38016083);
c = me.gg(c, d, a, b, k[15], 14, -660478335);
b = me.gg(b, c, d, a, k[4], 20, -405537848);
a = me.gg(a, b, c, d, k[9], 5, 568446438);
d = me.gg(d, a, b, c, k[14], 9, -1019803690);
c = me.gg(c, d, a, b, k[3], 14, -187363961);
b = me.gg(b, c, d, a, k[8], 20, 1163531501);
a = me.gg(a, b, c, d, k[13], 5, -1444681467);
d = me.gg(d, a, b, c, k[2], 9, -51403784);
c = me.gg(c, d, a, b, k[7], 14, 1735328473);
b = me.gg(b, c, d, a, k[12], 20, -1926607734);
a = me.hh(a, b, c, d, k[5], 4, -378558);
d = me.hh(d, a, b, c, k[8], 11, -2022574463);
c = me.hh(c, d, a, b, k[11], 16, 1839030562);
b = me.hh(b, c, d, a, k[14], 23, -35309556);
a = me.hh(a, b, c, d, k[1], 4, -1530992060);
d = me.hh(d, a, b, c, k[4], 11, 1272893353);
c = me.hh(c, d, a, b, k[7], 16, -155497632);
b = me.hh(b, c, d, a, k[10], 23, -1094730640);
a = me.hh(a, b, c, d, k[13], 4, 681279174);
d = me.hh(d, a, b, c, k[0], 11, -358537222);
c = me.hh(c, d, a, b, k[3], 16, -722521979);
b = me.hh(b, c, d, a, k[6], 23, 76029189);
a = me.hh(a, b, c, d, k[9], 4, -640364487);
d = me.hh(d, a, b, c, k[12], 11, -421815835);
c = me.hh(c, d, a, b, k[15], 16, 530742520);
b = me.hh(b, c, d, a, k[2], 23, -995338651);
a = me.ii(a, b, c, d, k[0], 6, -198630844);
d = me.ii(d, a, b, c, k[7], 10, 1126891415);
c = me.ii(c, d, a, b, k[14], 15, -1416354905);
b = me.ii(b, c, d, a, k[5], 21, -57434055);
a = me.ii(a, b, c, d, k[12], 6, 1700485571);
d = me.ii(d, a, b, c, k[3], 10, -1894986606);
c = me.ii(c, d, a, b, k[10], 15, -1051523);
b = me.ii(b, c, d, a, k[1], 21, -2054922799);
a = me.ii(a, b, c, d, k[8], 6, 1873313359);
d = me.ii(d, a, b, c, k[15], 10, -30611744);
c = me.ii(c, d, a, b, k[6], 15, -1560198380);
b = me.ii(b, c, d, a, k[13], 21, 1309151649);
a = me.ii(a, b, c, d, k[4], 6, -145523070);
d = me.ii(d, a, b, c, k[11], 10, -1120210379);
c = me.ii(c, d, a, b, k[2], 15, 718787259);
b = me.ii(b, c, d, a, k[9], 21, -343485551);
x[0] = me.add32(a, x[0]);
x[1] = me.add32(b, x[1]);
x[2] = me.add32(c, x[2]);
x[3] = me.add32(d, x[3]);
},
cmn: function(q, a, b, x, s, t) {
var me = this;
a = me.add32(me.add32(a, q), me.add32(x, t));
return me.add32((a << s) | (a >>> (32 - s)), b);
},
ff: function (a, b, c, d, x, s, t) {
return this.cmn((b & c) | ((~b) & d), a, b, x, s, t);
},
gg: function(a, b, c, d, x, s, t) {
return this.cmn((b & d) | (c & (~d)), a, b, x, s, t);
},
hh: function(a, b, c, d, x, s, t) {
return this.cmn(b^c^d, a, b, x, s, t);
},
ii: function(a, b, c, d, x, s, t) {
return this.cmn(c^(b | (~d)), a, b, x, s, t);
},
md51: function(s) {
var me = this;
txt = '';
var n = s.length,
state = [1732584193, -271733879, -1732584194, 271733878],
i;
for (i = 64; i <= s.length; i += 64) {
me.md5cycle(state, me.md5blk(s.substring(i - 64, i)));
}
s = s.substring(i - 64);
var tail = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];
for (i = 0; i < s.length; i++)
tail[i >> 2] |= s.charCodeAt(i) << ((i % 4) << 3);
tail[i >> 2] |= 0x80 << ((i % 4) << 3);
if (i > 55) {
me.md5cycle(state, tail);
for (i = 0; i < 16; i++)
tail[i] = 0;
}
tail[14] = n * 8;
me.md5cycle(state, tail);
return state;
},
md5blk: function(s) {
var md5blks = [],
i;
for (i = 0; i < 64; i += 4) {
md5blks[i >> 2] = s.charCodeAt(i)
+ (s.charCodeAt(i + 1) << 8 )
+ (s.charCodeAt(i + 2) << 16)
+ (s.charCodeAt(i + 3) << 24);
}
return md5blks;
},
hex_chr: '0123456789abcdef'.split(''),
rhex: function(n) {
var s = '',
j = 0;
for (; j < 4; j++)
s += this.hex_chr[(n >> (j * 8 + 4)) & 0x0F]
+ this.hex_chr[(n >> (j * 8)) & 0x0F];
return s;
},
hex: function(x) {
for (var i = 0; i < x.length; i++)
x[i] = this.rhex(x[i]);
return x.join('');
},
md5: function(s) {
return this.hex(this.md51(s));
},
add32: function(a, b) {
return (a + b) & 0xFFFFFFFF;
}
})

Include in app.js

requires: [ 'MyApp.util.Crypto']

Use like this:

alert(Crypto.md5('hello'));