//Note: All variables are unsigned 32 bits and wrap modulo 2^32 when calculating

//Initialize variables:
h0 := 0x67452301
h1 := 0xEFCDAB89
h2 := 0x98BADCFE
h3 := 0x10325476
h4 := 0xC3D2E1F0

//Pre-processing:
append a single "1" bit to message
append "0" bits until message length ≡ 448 ≡ -64 (mod 512)
append length of message (before pre-processing), in bits as 64-bit big-endian integer to message

//Process the message in successive 512-bit chunks:
break message into 512-bit chunks
for each chunk
    break chunk into sixteen 32-bit big-endian words w(i), 0 ≤ i ≤ 15

    //Extend the sixteen 32-bit words into eighty 32-bit words:
    for i from 16 to 79
        w(i) := (w(i-3) xor w(i-8) xor w(i-14) xor w(i-16)) leftrotate 1

    //Initialize hash value for this chunk:
    a := h0
    b := h1
    c := h2
    d := h3
    e := h4

    //Main loop:
    for i from 0 to 79
        if 0 ≤ i ≤ 19 then
            f := (b and c) or ((not b) and d)
            k := 0x5A827999
        else if 20 ≤ i ≤ 39
            f := b xor c xor d
            k := 0x6ED9EBA1
        else if 40 ≤ i ≤ 59
            f := (b and c) or (b and d) or (c and d)
            k := 0x8F1BBCDC
        else if 60 ≤ i ≤ 79
            f := b xor c xor d
            k := 0xCA62C1D6

        temp := (a leftrotate 5) + f + e + k + w(i)
        e := d
        d := c
        c := b leftrotate 30
        b := a
        a := temp

    //Add this chunk's hash to result so far:
    h0 := h0 + a
    h1 := h1 + b
    h2 := h2 + c
    h3 := h3 + d
    h4 := h4 + e

digest = hash = h0 append h1 append h2 append h3 append h4 //(expressed as big-endian)