Datasheet

Figure 43-5. Value Rval and Precomp in {nu1PrecompBase, RandPrecompLen}
43.3.5.4.9 CRT Service Modular Exponentiation Maximum Size
The following table details the maximum size in bits of P or Q, of N and of EP or EQ.
• The maximum size in bits of P or Q equals:
<Max Size Bits P> = <Max Size Bits Q> = 8 * <Max u2ModLength bytes>
• The maximum size in bits of N=P*Q equals:
<Max Size Bits N> = 2 * <Max Size Bits P>
• The maximum size in bits of EP or EQ equals:
<Max Size Bits EP> = <Max Size Bits EQ> = 8 * <Max u2ExpLength bytes>
• In case of the PUKCL_EXPMOD_EXPINPUKCCRAM option is specified, for the computation of the
maximum acceptable size, it is assumed the Exponent is entirely in the Crypto RAM and its length
equal the Modulus one.
• Otherwise, the Exponent is entirely out of the Crypto RAM and so the computation do not depend on
its length.
Table 43-66. CRT Service Maximum Sizes
Characteristics of the Operation P or Q Max Bit
Sizes
N Max Bit
Sizes
EP or EQ Max Bit Sizes
Exponent in Crypto RAM, 1 bit window 2912 5824 2912
Exponent in Crypto RAM, 2 bits window 2688 5376 2688
Exponent in Crypto RAM, 3 bits window 2464 4928 2464
Exponent in Crypto RAM, 4 bits window 2304 4608 2304
Exponent not in Crypto RAM, 1 bit window 3584 7168 <application dependent>
Exponent not in Crypto RAM, 2 bits window 3232 6464 <application dependent>
Exponent not in Crypto RAM, 3 bits window 2912 5824 <application dependent>
SAM D5x/E5x Family Data Sheet
Public Key Cryptography Controller (PUKCC)
© 2019 Microchip Technology Inc.
Datasheet
DS60001507E-page 1507