[Feature] Add Blob type that behaves like Bytes

[mattsse]

Component

consensus, eips, genesis

Describe the feature you would like

the current blob type is a fixedbytes alias allocated on the stack

alloy/crates/eips/src/eip4844/mod.rs

Lines 90 to 92 in 1ba17f2

	/// A Blob serialized as 0x-prefixed hex string
	pub type Blob = FixedBytes<BYTES_PER_BLOB>;

this is expensive to clone and has issues with StackOverflow in serde.

ideally we want a this to behave like Bytes but enforces the length at all times

we can solve this with a wrapper type Blob(Bytes) and only allow BYTES_PER_BLOB

but we need a way to transmute the blob to ckzg type so perhaps this should instead be Arc<FixedBytes<BYTES_PER_BLOB>>

so this will be problematic

alloy/crates/eips/src/eip4844/sidecar.rs

Line 274 in 1ba17f2

core::mem::transmute::<&[Blob], &[c_kzg::Blob]>(self.blobs.as_slice()),

so I think we can do this unless we change the ckzg validation interfaces
or we arc the entire sidecar, which would then be incompatible with the blobsbundlev1 type

Additional context

No response

[nadtech-hub]

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