sha1: Calculate a SHA1 hash of an object

In eddelbuettel/digest: Create Compact Hash Digests of R Objects

Calculate a SHA1 hash of an object

Description

Calculate a SHA1 hash of an object. The main difference with digest(x, algo = "sha1") is that sha1() will give the same hash on 32-bit and 64-bit systems. Note that the results depends on the setting of digits and zapsmall when handling floating point numbers. The current defaults keep digits and zapsmall as large as possible while maintaining the same hash on 32 bit and 64 bit systems.

Usage

sha1(x, digits = 14, zapsmall = 7, ..., algo = "sha1")
## S3 method for class 'numeric'
sha1(x, digits = 14, zapsmall = 7, ..., algo = "sha1")
## S3 method for class 'complex'
sha1(x, digits = 14, zapsmall = 7, ..., algo = "sha1")
## S3 method for class 'Date'
sha1(x, digits = 14, zapsmall = 7, ..., algo = "sha1")
## S3 method for class 'matrix'
sha1(x, digits = 14, zapsmall = 7, ..., algo = "sha1")
## S3 method for class 'data.frame'
sha1(x, digits = 14, zapsmall = 7, ..., algo = "sha1")
## S3 method for class 'array'
sha1(x, digits = 14, zapsmall = 7, ..., algo = "sha1")
## S3 method for class 'list'
sha1(x, digits = 14, zapsmall = 7, ..., algo = "sha1")
## S3 method for class 'pairlist'
sha1(x, digits = 14, zapsmall = 7, ..., algo = "sha1")
## S3 method for class 'POSIXlt'
sha1(x, digits = 14, zapsmall = 7, ..., algo = "sha1")
## S3 method for class 'POSIXct'
sha1(x, digits = 14, zapsmall = 7, ..., algo = "sha1")
## S3 method for class 'anova'
sha1(x, digits = 4, zapsmall = 7, ..., algo = "sha1")
## S3 method for class 'function'
sha1(x, digits = 14, zapsmall = 7, ..., algo = "sha1")

## S3 method for class 'formula'
sha1(x, digits = 14, zapsmall = 7, ..., algo = "sha1")
## S3 method for class ''(''
sha1(...)

sha1_digest(x, digits = 14, zapsmall = 7, ..., algo = "sha1")
## S3 method for class 'NULL'
sha1(...)
## S3 method for class 'name'
sha1(...)

sha1_attr_digest(x, digits = 14, zapsmall = 7, ..., algo = "sha1")
## S3 method for class 'call'
sha1(...)
## S3 method for class 'character'
sha1(...)
## S3 method for class 'factor'
sha1(...)
## S3 method for class 'integer'
sha1(...)
## S3 method for class 'logical'
sha1(...)
## S3 method for class 'raw'
sha1(...)
## S3 method for class 'environment'
sha1(...)
## S3 method for class ''<-''
sha1(...)

Arguments

x	the object to calculate the SHA1
digits	the approximate number of significant digits in base 10. Will be converted to a base 16 equivalent. Defaults to digits = 14, except for sha1.anova where digits = 4
zapsmall	the approximate negative magnitude of the smallest relevant digit. Will be converted to a base 2 equivalent. Values smaller than this number are equivalent to 0. Defaults to zapsmall = 7
...	If it is the only defined argument, passed to another sha1 method. If other arguments exist, see Details for usage.
algo	The hashing algorithm to be used by digest. Defaults to "sha1"

Details

sha1_digest() is a convenience function for objects where attributes cannot be added to apply the digest() function to its arguments. sha1_attr_digest() is a convenience function for objects where objects can be added to generate the hash. If generating hashes for objects in other packages, one of these two functions is recommended for use (typically, sha1_attr_digest()).

Extra arguments:

environment: An optional extra argument for sha1.function and sha1.formula should be TRUE, FALSE or missing. sha1.function and sha1.formula will ignore the environment of the function only when environment = FALSE.

Note

sha1 gained an algo argument since version 0.6.15. This allows sha1() to use all hashing algorithms available in digest(). The hashes created with sha1(x) from digest >= 0.6.15 are identical to sha1(x) from digest <= 0.6.14. The only exceptions are hashes created with sha1(x, algo = "sha1"), they will be different starting from digest 0.6.15

Until version 0.6.22, sha1 ignored the attributes of the object for some classes. This was fixed in version 0.6.23. Use options(sha1PackageVersion = "0.6.22") to get the old behaviour.

Version 0.6.24 and later ignore attributes named srcref.

Version 0.6.38 and later use digest() as a fallback for undefined methods. Note that this breaks the guarantee for identical hashes between 32-bit and 64-bit system. We recommend to write a custom method for such class. The basic idea is the convert the class in a list of classes that sha1 can handle. The project https://github.com/inbo/n2kanalysis/ demonstrates how to create custom sha1 dispatchers for other S3 classes, see file https://github.com/inbo/n2kanalysis/blob/main/R/sha1.R.

Author(s)

Thierry Onkelinx

eddelbuettel/digest documentation built on June 12, 2025, 8:53 a.m.