A private key of a public-private key pair with a corresponding identity is written to an integrated circuit including a processor, a non-volatile memory, and a cryptographic engine coupled to the processor and the non-volatile memory. The private key is written to the non-volatile memory. The integrated circuit is implemented in complementary metal-oxide semiconductor 14 nm or smaller technology. The integrated circuit is permanently modified, subsequent to the writing, such that further writing to the non-volatile memory is disabled and such that the private key can be read only by the cryptographic engine and not off-chip. Corresponding integrated circuits and wafers are also disclosed.