GitHub is enhancing the security of accessing Git data over SSH by introducing a new post-quantum secure SSH key exchange algorithm called sntrup761x25519-sha512, which will be implemented on September 17, 2025. This change aims to protect against potential future decryption attacks by quantum computers, though it does not affect HTTPS access or GitHub Enterprise Cloud with data residency in the US. The new algorithm combines the post-quantum secure Streamlined NTRU Prime with the classical Elliptic Curve Diffie-Hellman algorithm using the X25519 curve to maintain a security level at least equal to the classical method. Users with compatible SSH clients, like OpenSSH 9.0 or newer, will automatically use the new algorithm, while those with older clients will continue to operate with existing algorithms and are encouraged to upgrade for enhanced security benefits. GitHub will continue to monitor security developments and integrate additional post-quantum algorithms as they become supported by SSH libraries.