PSA Seed / Key Algorithm can be found by various ways, here is one: analyzing assembly from NAND dumps of various ECUs and searching for functions matching
.DNH_DNB_CLIENT_IMX6S_appli.elf.RO:423060C0 sub_423060C0 ; CODE XREF: sub_42306030+1A↑p
.DNH_DNB_CLIENT_IMX6S_appli.elf.RO:423060C0 ; sub_42306030+40↑p
.DNH_DNB_CLIENT_IMX6S_appli.elf.RO:423060C0 MOV R1, #0xB92143FB
.DNH_DNB_CLIENT_IMX6S_appli.elf.RO:423060C8 SMMUL.W R1, R1, R0
.DNH_DNB_CLIENT_IMX6S_appli.elf.RO:423060CC ADDS R1, R1, R0
.DNH_DNB_CLIENT_IMX6S_appli.elf.RO:423060CE ASRS R1, R1, #7
.DNH_DNB_CLIENT_IMX6S_appli.elf.RO:423060D0 SUB.W R1, R1, R0,ASR#31
.DNH_DNB_CLIENT_IMX6S_appli.elf.RO:423060D4 MOVS R2, #0xB1
.DNH_DNB_CLIENT_IMX6S_appli.elf.RO:423060D6 SMULBB.W R2, R1, R2
.DNH_DNB_CLIENT_IMX6S_appli.elf.RO:423060DA SUBS R0, R0, R2
.DNH_DNB_CLIENT_IMX6S_appli.elf.RO:423060DC MOVS R2, #0xAB
.DNH_DNB_CLIENT_IMX6S_appli.elf.RO:423060DE SMULBB.W R0, R0, R2
.DNH_DNB_CLIENT_IMX6S_appli.elf.RO:423060E2 SUB.W R0, R0, R1,LSL#1
.DNH_DNB_CLIENT_IMX6S_appli.elf.RO:423060E6 SXTH R0, R0
.DNH_DNB_CLIENT_IMX6S_appli.elf.RO:423060E8 CMP R0, #0
.DNH_DNB_CLIENT_IMX6S_appli.elf.RO:423060EA ITTT LT
.DNH_DNB_CLIENT_IMX6S_appli.elf.RO:423060EC MOVLTW R1, #0x763D
.DNH_DNB_CLIENT_IMX6S_appli.elf.RO:423060F0 ADDLT R0, R0, R1
.DNH_DNB_CLIENT_IMX6S_appli.elf.RO:423060F2 SXTHLT R0, R0
.DNH_DNB_CLIENT_IMX6S_appli.elf.RO:423060F4 BX LR
Each ECU has his own key, which can be found inside calibration files or using bruteforce to find matching key using a couple of seed/key pairs generated from official diagnostic tool - which is very fast to do because ECU key is only 2 bytes long -