DS1963S

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The sequence Kt (0 £ t £ 79) is defined as follows:

Kt

:=

5A827999h

(0

£ t £ 19)

6ED9EBA1h (20

£ t £ 39)

8F1BBCDCh (40

£ t £ 59)

CA62C1D6h (60

£ t £ 79)

The variables A, B, C, D, E are initialized as follows:

A

:=

67452301h

B

:=

EFCDAB89h

C

:=

98BADCFEh

D

:=

10325476h

E:=

C3D2E1F0h

The 160-bit MAC is the concatenation of A, B, C, D, and E after looping through the following set of

computations for t = 0 to 79 (discarding any carry-out):

TMP :=

S5(A) + ft(B,C,D) + Wt + Kt + E

E:=

D

D:=

C

C:=

S30(B)

B:=

A

A:=

TMP

The Message Authentication Code is loaded into the scratchpad of the DS1963S in two different ways,

depending on the selected SHA function. With Compute First Secret and Compute Next Secret 64 bits of

the MAC are used in a repeating pattern in order to allow it to be copied to any of the eight secrets. With

all other SHA functions the full 160-bit result is loaded into the scratchpad. Table 4 shows the placement

of bytes in the scratchpad.

SHA-1 Output Message Formats Table 4

Partial Code (Compute First Secret and Compute Next Secret only)

(SP+0) := E[7:0]

(SP+1) := E[15:8]

(SP+2) := E[23:16]

(SP+3) := E[31:24]

(SP+4) := D[7:0]

(SP+5) := D[15:8]

(SP+6) := D[23:16]

(SP+7) := D[31:24]

(SP+8) := E[7:0]

(SP+9) := E[15:8]

(SP+10) := E[23:16]

(SP+11) := E[31:24]

(SP+12) := D[7:0]

(SP+13) := D[15:8]

(SP+14) := D[23:16]

(SP+15) := D[31:24]

(SP+16) := E[7:0]

(SP+17) := E[15:8]

(SP+18) := E[23:16]

(SP+19) := E[31:24]

(SP+20) := D[7:0]

(SP+21) := D[15:8]

(SP+22) := D[23:16]

(SP+23) := D[31:24]

(SP+24) := E[7:0]

(SP+25) := E[15:8]

(SP+26) := E[23:16]

(SP+27) := E[31:24]

(SP+28) := D[7:0]

(SP+29) := D[15:8]

(SP+30) := D[23:16]

(SP+31) := D[31:24]

Full 160-Bit Code (all other SHA functions)

(SP+8) := E[7:0]

(SP+9) := E[15:8]

(SP+10) := E[23:16]

(SP+11) := E[31:24]

(SP+12) := D[7:0]

(SP+13) := D[15:8]

(SP+14) := D[23:16]

(SP+15) := D[31:24]

(SP+16) := C[7:0]

(SP+17) := C[15:8]

(SP+18) := C[23:16]

(SP+19) := C[31:24]

(SP+20) := B[7:0]

(SP+21) := B[15:8]

(SP+22) := B[23:16]

(SP+23) := B[31:24]

(SP+24) := A[7:0]

(SP+25) := A[15:8]

(SP+26) := A[23:16]

(SP+27) := A[31:24]