Appendix B: IPv6 Address Normalization

Normalized IPv6 addresses are required for upload into DataX. IPv6 addresses must be normalized according to RFC 5952 normalization rules, so that the data can be 100% accurately matched after encryption. If IPv6 addresses are not normalized, a single IP address can be written in multiple valid formats (e.g., 2001:db8:0:0::1 and 2001:0db8::0001).

Important

• Submitting /64 prefixes or other CIDR blocks is not supported.

• IPv4-Mapped IPv6: Do not submit addresses like ::ffff:192.168.1.1. Please hash the original IPv4 address instead.

Normalization Rules (RFC 5952)

Normalize IPv6 addresses as follows:

1. Suppress Leading Zeros: Leading zeros in each 16-bit group must be removed.

   • 2001:0db8 → 2001:db8

2. Longest Zero Run (::): Use :: to replace the longest consecutive sequence of all-zero groups.

   • 2001:db8:0:0:0:0:0:1 → 2001:db8::1

3. Tie-breaking: If there are two zero runs of equal length, compress the first (leftmost) one.

   • 2001:db8:0:0:1:0:0:1 → 2001:db8::1:0:0:1

4. No Single Group Compression: Do not use :: to replace a single 16-bit zero group. Use :0: instead.

   • 2001:db8:0:1:0:0:0:1 → 2001:db8:0:1::1

5. Lowercase: All hexadecimal characters must be lowercase.

   • 2001:DB8:AAAA::1 → 2001:db8:aaaa::1

Verify Normalized IPv6 Addresses

The normalized IPv6 address must be verified using SHA256 hashing. The hash input must be the UTF-8 encoded normalized string with no trailing newline.

To Verify the Normalized IPv6 Address:

Run echo -n "2001:db8::1" | sha256sum in the terminal. The output must be 5afd19e...1ed536. If it differs, the normalization or encoding is wrong.

Important

Trailing Newline

• Many echo commands add a \n which completely changes the hash. Always use echo -n.

Examples of Normalized IPs

The following are examples of normalized IPv6 addresses with their hash results.