Computes a cryptographic SHA256-hashing of the given input field or array of fields. The hashed output is returned as a hex string, meaning the hexadecimal representation of the SHA256 hash of data.

This function can be used to calculate checksums to compare outside of LogScale or collect multiple fields into a combined string of fixed length.

ParameterTypeRequiredDefault ValueDescription
asstringoptional[a] _sha256 The name of the output field.
field[b]array of stringsrequired   The name of the field or fields to hash.

[a] Optional parameters use their default value unless explicitly set.

[b] The parameter name field can be omitted.

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crypto:sha256() Function Operation

crypto:sha256() hashes the UTF-8 encoding of the fields.

When providing more than one field:

  • The function hashes the concatenation of the fields.

  • If a given field is missing from an event — or if it has an empty value — it is treated as the empty string.

Click + next to an example below to get the full details.

SHA-256 Hash Multiple Fields

SHA-256 hash multiple fields using the crypto:sha256() function

Query
logscale
crypto:sha256(field=[a,b,c])
Introduction

In this example, the crypto:sha256() function is used to hash the fields a,b,c and return the result into a field named _sha256.

Step-by-Step

  1. Starting with the source repository events.

  2. logscale
    crypto:sha256(field=[a,b,c])

    Performs a cryptographic SHA256-hashing of a,b,c. The field argument can be omitted to write: crypto:sha1([a,b,c])

  3. Event Result set.

Summary and Results

The query is used to encode a string using the SHA-256 hash. When called with multiple values, crypto:sha256() function creates a single SHA-256 sum from the combined value of the supplied fields. Combining fields in this way and converting to an SHa-256 can be an effective method of creating a unique ID for a given fieldset which could be used to identify a specific event type. The SHA-256 is reproducible (for example, supplying the same values will produce the same SHA-256 sum), and so it can sometimes be an effective method of creating unique identifier or lookup fields for a join() across two different datasets.

SHA-256 Hash a Field With a Given Value

SHA-256 hash a field with a given value using the crypto:sha256() function

Query
logscale
a := "Hello, world!"
| crypto:sha256(a)
Introduction

In this example, the crypto:sha256() function is used to hash the field a with value Hello, world! and convert the result into _sha256.

Step-by-Step

  1. Starting with the source repository events.

  2. logscale
    a := "Hello, world!"

    Assigns the value Hello, world! to the field a.

  3. logscale
    | crypto:sha256(a)

    Performs a cryptographic SHA-256-hashing of a:= "Hello, world!". The output value would be _sha256 = "315f5bdb76d078c43b8ac0064e4a0164612b1fce77c869345bfc94c75894edd3"

  4. Event Result set.

Summary and Results

The query is used to encode a string using the SHA-256 hash. The hash generators MD5, SHA-1, and SHA-256 are, for example, useful for encoding passwords or representing other strings in the system as hashed values.