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Solana Transaction Data Encoding & Decoding
Solana smart contracts (programs) communicate with clients through
structured binary data that needs to be properly encoded and decoded
to ensure correct interpretation.
Binary Encoding Basics
Solana transaction data is encoded in a compact binary format to
minimize transaction size and reduce fees. Each data type has a
specific binary representation:
-
Integer types (u8, u16, u32, u64, u128, i8, i16,
i32, i64, i128) are stored in little-endian byte order
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Boolean values are stored as a single byte (1 for
true, 0 for false)
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Public keys are stored as 32-byte arrays
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Strings and byte arrays are prefixed with a 4-byte
length (u32) followed by the actual bytes
Anchor Program Format
Programs built with the Anchor framework use an 8-byte discriminator
at the beginning of instruction data:
// Transaction data structure with Anchor
[8-byte discriminator][instruction data]
The discriminator is the first 8 bytes of the SHA-256 hash of the
instruction's name, which uniquely identifies which instruction should
be executed.
Base58 Encoding
For readability and efficient representation in UIs, Solana often uses
Base58 encoding for binary data:
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Base58 uses the characters 1-9, A-Z, a-z, excluding 0, O, I, and l
(to prevent visual confusion)
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It's more compact than hex encoding while remaining URL-safe
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Public keys and transaction signatures are commonly displayed in
Base58 format
Why Encoding/Decoding Matters
Proper encoding and decoding is critical for:
-
Security - Ensuring data is interpreted correctly
and doesn't cause unexpected behavior
-
Efficiency - Minimizing transaction size to reduce
fees
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Interoperability - Enabling different clients to
interact with the same programs
-
Debugging - Helping developers understand and
troubleshoot transaction data
For more information, see the
official Solana documentation on transaction instructions
and
Anchor Framework documentation .