feat(mlkem_top): parameterize K in {2,3,4} (ML-KEM 512/768/1024)
Generalize KeyGen from K=2-hardcoded to compile-time parameter K:
- eta1 derived (3 for K=2, else 2); slot layout SLOT_S/E/T = K*K+{0,K,2K},
NUM_SLOTS = K*K+3K; SAW=5 slot-addr width.
- A-stage: explicit a_i/a_j row-major counters (slot = i*K+j) instead of
K=2 bit-tricks. C/N stages: parametric slot bases, 2K polys.
- M-stage: m_i/m_j widened to 3-bit (must reach K=4); slots i*K+j etc.
- E-stage: 2K polys, e_is_dk split, rho offset 384*K.
- H(ek): H_NBLK=ceil((EK_BYTES+1)/136), H_LAST padding generalized;
h_blk 4-bit. Byte mems sized EK_BYTES/DK_BYTES.
- Widen dbg_byte_idx_i to [10:0] (ek up to 1568B for K=4).
Parametric TB (tb_mlkem_kg_katK, KP generic + CASE plusarg). Verified
byte-exact vs NIST KAT:
K=2 (512): cases 0..4 ek 800B / dk 1632B
K=3 (768): cases 0..2 ek 1184B / dk 2400B (~36k cyc)
K=4 (1024): cases 0..2 ek 1568B / dk 3168B (~54k cyc)
run_tb.sh top runs all three parameter sets.
FallenSigh
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